Healthy Eating | Dr Briffa's Blog

Nonsense study being used to claim that meat causes weight gain

There’s a study doing the rounds that is being reported as evidence that ‘Atkins’ was wrong’. Apparently, according to those reporting the study, it shows that eating more meat generally causes increased weight gain over time [1]. To see a typical way in which this study is being reported, see here.

Sitting on a plane yesterday I read this study in its entirety. And even cursory inspection of it reveals some things which some journalists and reporters may have missed.

The first, most obvious, thing to note is that the study is epidemiological in nature. It looked at a total of 16 female and 13 male populations over some years, and when all the results were lumped together there was, apparently, an association between meat eating and enhanced weight gain over time. Eating an additional 250 g of meat each day appeared to translate into an extra 2 kg over five years. The authors of the study state “This absolute increase may be considered low from a clinical point of view.”

But getting back to the epidemiological nature of the study, we know that, at best, all the we can infer from this study is that meat-eating is associated with weight gain. That does not meat it causes weight gain. Other so-called ‘confounding factors’ (maybe big meat-eaters ate other foods that were ‘fattening’, and that’s the real explanation behind the finding, for instance). Now, the authors attempted to control for these ‘confounding factors’, but this is always an imprecise science. Certainly, there was no attempt in this study to consider the relationship of other major foods (e.g. bread, pasta) and weight gain.

Other problems associated with this study include the fact that diets were assessed with a questionnaire once (at the beginning of the study) and never again, and that weight was generally self-reported (and this can be prone to mis-reporting). The other thing, of course, is that weight tells us practically nothing about health. Body composition would be a much better judge here. Maybe, if meat really does lead to increased weight, this might be in the form of muscle, rather than fat. Who is to know? Well we can’t know, because this study looked at weight alone, and tells us nothing therefore about changes in body composition.

So, these are just some of this studies major deficiencies.

What other evidence might we look to then? Well, to really look dissect the truth about the impact of a food (e.g. meat) or macronutrient (e.g. protein, fat) on weight and/or health, we require intervention studies. Put people, say, on a high meat/protein diet, for instance, and see what happens. Well, studies show that such a diet, compared to a low-fat diet, generally leads to improvements in terms of weight loss and markers of cardiovascular disease and diabetes.

The authors of the study actually acknowledge the evidence showing that effectiveness of higher protein diets in weight loss, stating “…studies performed in overweight or obese subjects under energy restriction did observe a higher weight loss with a high-protein diet than with a high-carbohydrate diet.” They even list several studies that support this. The authors also concede that most studies show that when carbohydrate is partially replaced by meat, no weight change occurs.

Yet, even after these acknowledgements, the authors go on later to declare that “[More] importantly, our results do not support that a high-protein diet prevents obesity or promotes long-term weight loss, contrary to what has been advocated.”

What the authors seem to be saying here is that we should ignore abundant interventional (good) evidence that a meat/protein rich diet is good for weight control, and we take more note of their low quality epidemiological (basically, useless) evidence.

Also, while this study did find, overall, an association between higher meat eating and weight gain when all the results were lumped together, the results were highly ‘heterogenous’. This means, in this case, the results varied a lot between populations. This is particularly relevant, as when look between two populations (e.g. UK residents and those living in France) there is huge potential for confounding. When we look at a single population, then the risk of this is reduced.

Looking at single populations, the authors found a link between higher meat eating and weight gain in 6 populations. However, there was NO SUCH LINK in the remaining TEN populations studied.

And here’s another thing. There was evidence in certain populations that higher meat eating might actually protect against weight gain. And that lower meat consumption might promote weight gain.

In men, the population eating the most meat, actually had only the second highest gain in weight. The population eating the least meat, had the 10th highest weight gain (out of 13).

In women, the population eating the 12th highest amount of meat (Spain), actually had the lowest weight gain overall. Oh, and Danish women ate the most meat, but only one population enjoyed less weight gain than them.

You are at liberty, of course, to make of this study what you will. I’ll tell you what I make of it though: it’s not worth the paper it’s written on. Actually, worse than that, it appears to be wholly misleading.

References:

1. Vergnaud A-C, et al. Meat consumption and prospective weight change in participants of the EPIC-PANACEA study. Am J Clin Nutr 2010;92:398-497

Multivitamin and mineral supplementation found to help fat loss and speed metabolic rate

While I am interested in many aspects of health, and in particular providing information that individuals can use to exert more control over their health and wellbeing, I do confess to having a particular interest in weight loss. One reason for this is that its an issue that is quite commonly on people’s mind. As our collective weight and waistlines expand, so does the number of people wanting to shed their excess baggage. The other reason why I have an interest in this area concerns what I believe to be a misguided approach to weight loss based on the calorie principle.

I go through the detail of this in my latest book (Waist Disposal). You can read what I believe to be the major issues here. For those not inclined to go back and read this earlier post, here’s the key points transcribed:

“Conventional advice dictates that weight loss depends on simply eating less or exercising more. Curiously, though, research reveals that there is no good evidence that either of these approaches leads to sustained, meaningful weight loss. The normal retort is that failed slimmers must be ‘cheating’. But could the real reason for failure here be not self-delusion, but a fundamental problem with the calorie-based theory of weight loss?

For example, one reason why eating less may not be effective for long term weight loss is that it can cause the metabolism to stall (if you don’t put much fuel on a fire, it doesn’t burn so well). Plus, calorie-conscious individuals tend to cut the fat in favour or carbohydrate. However, it is carbohydrate that is mainly responsible for the secretion of insulin – the hormone that is chiefly responsible for the deposition of fat in the body.

Another problem with eating less is, well, hunger. And while we might be able to put with this for awhile, in the long term going hungry makes conventional approaches to weight loss quite unsustainable.”

The bottom line is that the way we conventionally think about weight loss (based on the calorie principle) makes significant, sustained weight loss hard to achieve. And I’m not into making this hard for people. I genuinely believe in helping individuals achieve their health goals easily. And that’s a major motivation behind me not perpetuating the calorie principle mantra that so often causes people to end up hungry and demoralised (and, usually, overweight too).

As I wrote in the blog post linked to above:

“In reality, the key to successful, sustainable weight loss is to eat a diet that truly satisfies (so no hunger), but at the same time induces relatively little in the way of insulin.”

What this means, essentially, is eating a relatively low-carb, protein-rich diet based on meat, fish, eggs, nuts, seeds, vegetables and some fruit. It’s a ‘primal’ or ‘paleo’ diet. It’s eating a bit like a caveman (or cavewoman). For most people, successful weight loss in the long term is really is as simple (and as easy) as that.

Because I like things to be easy, I’m interested in little tricks and tools that can aid individuals achieving their health goals with minimal effort. Getting a bit more sleep (by getting into bed a bit earlier) and getting more sun exposure are examples of this. But getting back to the weight loss theme, I was interested to read a recent study which examined the effects of supplementing women with nutrients, in terms of the apparent effect of this on, among other things, weight and fatness [1].

About 100 overweight (average body mass index 28) women aged 18-55 were treated with one of the folowing:

1. a multivitamin and mineral tablet
2. calcium (162 mg per day)
3. a placebo (inactive medication)

The study lasted a total of six months. A number of measurements were taken including body weight, body mass index (BMI), fat mass and waist circumference.

Those taking the multivitamin and mineral, compared to those taking placebo, saw significant falls in body weight, BMI and fat mass.

Why? Well, another measure monitored in this study was ‘resting energy expenditure’ (the amount of energy consumed by the body at rest). This was found to be up in the group taking the multivitamin and mineral. This finding suggests that taking the nutrient supplement sparked a little more life into the metabolisms of the ladies in this study.

Perhaps of some significance is the fact that those taking the multivitamin and mineral saw a fall in a physiological measurement known as the ‘respiratory quotient’. This is assessed by measuring the amount of oxygen an individual uses and comparing that with the amount of carbon dioxide they release in their breath. Respiratory quotients vary between 0.7 and 1.0. Lower values suggest better fat-burning in the cells. Although the fall in the respiratory quotient seen in those taking a multivitamin and mineral did not quite reach statistical significance, this finding suggests that nutrient supplementation might have the potential to enhance fat-burning in the body.

Now, this is one study, and it was done in women (and not men), so I don’t think we’re at a stage where we can recommend nutrient supplementation as some sort of fat loss panacea. However, the idea that nutrient supplementation might aid weight control and fat burning is not too far-fetched: the reactions that convert food into energy in the body depend, to a degree, on ‘co-factors’, many of which are nutrients found in multivitamin and mineral supplements.

References:

1. Li Y, et al. Effects of multivitamin and mineral supplementation on adiposity, energy expenditure and lipid profiles in obese Chinese women. International Journal of Obesity (2010) 34, 1070–1077

More evidence suggests that rapid weight loss leads to better results than slower progress

There’s a commonly-held notion that as far as weight loss is concerned, slow and steady wins the day. In other words, gradual weight loss (often advised in the order of 1-2 pounds a week) leads to better long term results than more rapid loss. I wrote about this back in May. This blog focused on a study which linked more rapid initial weight loss with better outcomes in the long term.

I was interested, therefore, to read about a recently-announced study which essentially found the same thing.

This research, presented this week at the International Congress on Obesity in Stockholm, Sweden, focused on Australian individuals weighing about 100 kg (220 lbs). Some of the group were prescribed a diet designed to lead to weight loss of about 1.5 kg per week over a 12-week period. The others were prescribed a diet designed to lose about 0.5 kg per week over 36 weeks. In theory, total weight loss should have been about the same across the two groups.

In reality, though, the ‘rapid weight loss’ group did better. 78 per cent of this group achieved a loss equating to at least 15 per cent of their body weight. In the slow-losing group, less than half (48 per cent) achieved this goal.

The long-term results of these two interventions remain to be seen. However, the article linked to also mentions other research, this time from the Netherlands, which found that weight loss one year after intervention was higher for those with a higher initial weight loss.

Also, the study that I wrote about in May found better results in those who lost weight more rapidly did better over the course of the diet, and also had better results after a further year of ‘maintenance’.

All-in-all, therefore, what we have here is more than a little evidence suggesting that more rapid weight loss produces better results, even in the longer term.

One commenter (Jamie) after the May blog alluded to the point to that perhaps that some forms of rapid weight loss are healthier than others. A diet of salads and soups (semi-starvation) coupled with lots of aerobic exercise may not be the best way forward in the long term. On the other hand, a diet based on primal foods (e.g. meat, fish, eggs, nuts, seeds, vegetables and some fruit) may allow rapid weight loss, with no undue hunger, and no real risk of malnutrition either. I couldn’t agree more. In my view, using such a healthy and sustainable strategy may well lead individuals to lose weight and fat very quickly, but not too quickly.

Not just what you eat, but how much believe you’ve eaten, determines how satisfying food is

When it comes to advising about what to eat for fat loss, I’m very much into quality over quantity. Eating a protein-rich diet which is relatively low in carb tends to work very well for the purposes of fat loss, even when no restriction is placed on calorie intake. Why? Well, one reason might be that certain carbs (those that disrupt blood sugar the most) are uniquely fattening, primarily through their influence on the ‘fat storage’ hormone insulin. However, even if this is not true, a major boon of these diets is that fact that they tend to be, calorie for calorie, more satisfying that say higher-carb diets.

What this means in practice is that when individuals accustomed to eating a typical (high-carb) Western diet switch to one lower in carb and richer in protein, they generally automatically eat less because they’re less hungry. Other simple tactics for quelling any tendency to overeat include avoiding foods that can stimulate appetite including those containing artificial sweeteners or laced with monosodium glutamate (MSG). Strategies for putting a natural brake on the appetite are explored in the chapter entitled ‘Satisfaction Guaranteed’ in my latest book (Waist Disposal).

However, how satisfying we find food to be (and how much we eat of it) is not purely down to its chemical make-up. It has for a long time been known that, for instance, food intake can be influence by its proximity, setting (e.g. eating in front of the TV tends to lead to overeating), who you’re eating food with, and the amount served to us or we serve ourselves.

I’m not into the idea of people ‘going hungry’ when they serve themselves food, but there’s no doubt that some of us can be prone to overeating when food supply is plentiful. So, one little trick that can work here at home, is eating food off smaller plates. Personally, if I’m at home, I eat my lunch or dinner off a large-ish side plate (rather than a dinner plate). My decision about which plate to use is based purely on my level of hunger.

I was thinking about this today while reading about a study presented recently at a scientific meeting in Pittsburgh, Pennsylvania, USA. You can read about the study here.

The study was designed to test the effect of perceived food intake on the satisfaction derived from the food. The research comprised two parts. In the first experiment, individuals consumed a fruit smoothie. The individuals in this study were shown a picture purported to represent the whole fruit in the smoothie. Half the people were shown a picture of a small amount of fruit. The other half were shown a photo with more fruit in it. It turns out that, overall, those who were shown the photo with more fruit in it were more satisfied (even though they consumed the same amount of smoothie as the other group).

In a second experiment, researchers manipulated the ‘actual’ and ‘perceived’ amount of soup that people consumed. “Using a soup bowl connected to a hidden pump beneath the bowl, the amount of soup in the bowl was increased or decreased as participants ate, without their knowledge. Three hours after the meal, it was the perceived (remembered) amount of soup in the bowl and not the actual amount of soup consumed that predicted post-meal hunger and fullness ratings.”

What’s this got to do with people eating off smaller plates? Well, it occurred to me that perhaps putting a given portion of food on a smaller plate makes it look bigger, and therefore we perceive it as bigger, and perhaps get more satisfaction from it than we otherwise would.

A lot of the research on the factors that drive food intake (other than the food itself) has been done by Dr Brian Wansink. His book, Mindless Eating, is a thought-provoking and entertaining account of unconscious influences on what and how much we eat, and the simple steps we can take to reduce any tendency to over-consume food and drink. More about this book and Brian Wansink’s work can be found here.

Mysterious bitter taste in my mouth turns out to have simple solution

When in practice, I get to see a fair number of individuals who have traditionally perplexing health issues. Over the past couple of weeks I experienced a mysterious issue of my own. And I had no idea what was causing it. The symptoms? A bitter, metallic-like taste in my mouth, but only when I ate. Pretty much everything I ate would bring on this symptom, though it would fade quite quickly after eating.

When I have experiences such as this, it’s not my way generally to panic or over-analyse (as perhaps evidenced by the fact that I have had only one doctor’s consultation in the last 20-odd years). I am agreat believer in the self-healing powers of the body, and that most things are self-righting. Sometimes, the best thing to do about an illness or symptom is nothing at all.

Sure enough, after about a week, the symptom disappeared. And I thought nothing more of it, until this morning, when I think I accidentally unearthed what caused my taste-related symptoms. I came across this in a US on-line newspaper. It seems that the cause of my symptoms was pine nuts. Apparently, I was suffering from what is being termed ‘pine mouth’. Eating pines can lead to a bitter/metallic taste in the mouth that can last for days. No-one seems to know what, precisely, is causing the problem, though.

10 days ago I ate some pine nuts as part of salad I had made to accompany some barbeque food. Now I think back, it’s after that that my symptoms developed. I can’t be 100 per cent sure when they disappeared, but think it was the following Saturday (6 days later).

It occurs to me that pine nuts are a reasonably commonly-eaten food. I imagine, therefore, that ‘pine mouth’ is reasonably common. Until this morning, I honestly had not even heard of ‘pine mouth’. I’m hoping this blog might raise some awareness about this issue, and prevent any undue anxiety or needless consultations with healthcare practitioners.

Are wholegrains good for the heart?

The conventional nutritional approach for ‘heart health’ is a low-fat (specifically, low saturated fat), high-carbohydrate diet. For many reasons, this is not the sort of diet I would generally recommend to ward off heart disease. For more about this, click here.

One particular form of carbohydrate that has been vigorously promoted for its heart-healthy properties are the ‘wholegrains’ such as wholemeal bread and brown rice. The pushing of wholegrains appears to be backed by studies which allegedly find that those who eat more wholegrains tend to have a reduced risk of heart disease. However, these studies are epidemiological in nature, and by virtue of this can only really tell us about the association wholegrains have with heart disease, but in no way indicate that wholegrains actually reduce heart disease risk.

One major issues of studies of this nature is that they are prone to ‘confounding’. Essentially, the benefits associated with wholegrain consumption might not be due to wholegrain at all, but other things to do with wholegrain eaters. Wholegrains have been vigorously promoted as ‘healthy’ for ages now, and as a result, those who eat them are likely to be more health-conscious than those who don’t.

So, wholegrain eaters might, for example, exercise more, be less likely to be obese and smoke less than those who eat more refined grains. And it might be these factor that account for the apparent benefits of wholegrain eating.

One way to find out for sure whether wholegrains really are good for the heart is to conduct so-called intervention studies. What this would mean, in essence, would be to take a group of individuals, and randomise them to eating either a diet rich in wholegrain or a control diet (not rich in wholegrains), and then see over time if the wholegrain eaters ended up being protected from heart disease. I don’t believe such a study has ever been done.

The next best thing, perhaps, would be to do the same thing, but instead of monitoring heart disease risk, monitor ‘surrogate markers’ of heart disease instead. Surrogate markers for heart disease include factors include things like body weight and fatness, waist circumference, blood chemistry (e.g. glucose and insulin levels), inflammation, endothelial function (a measure of the health of the inside of the body’s arteries) and blood clotting. A recent study did just this [1].

In this study, 316 individuals aged 18-65 were randomised to one of three diets:

1. A diet which included 60 g of wholegrain each day for 16 weeks

2. A diet which included 60 g of wholegrain each day for 8 weeks, followed by 120 g of wholegrain for a further 8 weeks

3. A control diet (no dietary change, in which wholegrain consumption was less than 30 g per day) for 16 weeks

At the end of the study, there was no significant difference in any of the surrogate markers for heart disease tested.

Now, of course there are several potential explanations for these ‘disappointing’ findings including, perhaps, the fact that the study did not go on for long enough. However, four months is usually long enough to see quite dramatic changes in surrogate markers for cardiovascular disease, as long as the approach taken is correct.

It is perhaps the case that wholegrains and healthier than their refined counterparts. But they are still grains, and can still have relatively high glycaemic index (and glycaemic load) if eaten in quantity. As I have reported before, diets of relatively high GI and/or GL are associated with enhanced risk of cardiovascular disease. See here for more about this.

So, what might be better than adding wholegrain to the diet for reducing cardiovascular disease risk? I suggest taking grains out (or at least eating them in generally limited quantities). There is evidence that low-carb diets, compared to low-fat ones, lead to improvements in many surrogate markers of disease including serum glucose, measures of insulin resistance, triglyceride levels and high-density lipoprotein cholesterol levels [2].

And the other thing about low-carb diets is that they can really make a difference to body fatness, especially ‘abdominal obesity’. I had an email today from a fellow who had read my latest book (Waist Disposal), employed its advice, and promptly lost four inches (10 cm) off his waist in 5 weeks. I didn’t quiz him about precisely what he’s been eating, though I wouldn’t be surprised if the benefits he’s seen have been achieved without the ‘aid’ of wholegrains.

References:

1. Brownlee IA, et al. Markers of cardiovascular risk are not changed by increased whole-grain intake: the WHOLEheart study, a randomised, controlled dietary intervention B J Nutr 2010;104(1):125-134

2. Samaha FF, et al. Low-carbohydrate diets, obesity, and metabolic risk factors for cardiovascular disease. Curr Atheroscler Rep 2007;9(6):441-71

Study reminds us of the superior performance of low-carb diets over low-fat ones for weight loss

Where weight loss is concerned, there are many ways to skin a cat. But the two most commonly applied dietary strategies are low-fat and low-carb. This week I came across a report of a study here in which obese women were put on either a ‘low-fat’ or ‘lower-carb’ diet for a period of 12 weeks. Women in this study were supplied with appropriately made-up and calorie-controlled meals.

This is the carbohydrate:fat:protein breakdown of the two prescribed diets:

Low-fat – 60:20:20

Lower-carb – 45:35:20

The report of the study in question does not give us much more detail about these diets, other than the fact that the low-carb diet fatty component came largely from unsaturated fats (such as those found in nuts). We do not know, however, potentially important information such as the quality of carbohydrate in each diet. However, assuming that calorie intake is about 1500 calories per day, and knowing that there are about 4 calories in each gram of carb, we can calculate that the ‘low-carb’ diet offered up about 170 grams of carb.

This is indeed lower-carb than the low-fat diet deployed in this study. However, it’s still actually high in carbs compared to true ‘low-carb’ diets which are often advocated (including by me) for the purposes of weight loss.

Nevertheless, the reported results from this study show that the women eating the lower-carb diet lost an average of 3.4 lbs (1.5 kg) more than the other group (an average of 19.6 lbs v 16.2 lbs). This despite the fact that the women were, supposedly, eating the same number of calories.

I say supposedly because while the women were supplied with their food, there’s no assurance that they ate all of it and/or didn’t eat additional food. However, there is other evidence that suggests a calorie is not a calorie after all. See here for more about this.

The other thing worth mentioning about this study is the fact that it was performed in ‘insulin resistant’ women (as adjudged by fasting insulin levels). Generally, therefore, these women would not do a good job of processing carbohydrate, and would perhaps have most to gain from a lower-carbohydrate diet.

Our ability to learn much from this diet maybe limited, but it at least reminded me of the fat that low-carb diets generally outperform low-fat ones in the weight loss stakes. I reviewed the evidence in the area for my latest book, Waist Disposal. Here’s the relevant passage from the book (referencing has been adjusted for ease):

To date, seven studies have pitted low-carb against low-fat over various lengths of time. The shortest of these lasted three months.6 The average weight loss on the low-carb diet was almost 10 kg. This compared very favourably with the weight loss on the low-fat diet, which averaged just over 4 kg.

The remaining six trials lasted at least six months [1-7]. All of these trials found that after six months, weight loss on the low-carb diet was significantly superior to that on the low-fat diet.

Four of the studies went on for a whole year. Two of these studies did not find a significant difference in weight loss between the two groups at the end of the study. In one study, compliance was monitored, and it turned out that most participants did not cut their carb consumption to the level they were asked to. In another study, there was no checking of compliance at all. In other words, it is just not known whether the study participants restricted carbohydrate to the extent they were instructed to. The two other year-long [4,6] studies did, however, find that the low-carb diet significantly outperformed the low-fat one in terms of weight loss.

To get an idea of the relative effectiveness of low-carb versus low-fat diets, we can tot up the average weight losses with each diet in all the studies, and divide this by the number of studies to get the average weight loss:

• for the low-carb diets, average weight loss was 9 kg

• for the low-fat diets, it was 4.5 kg.

Do you see a relationship here? Yes, that’s right – overall, those on low-carb diets lost precisely twice as much weight as those slowly starving and depriving themselves on low-fat regimes.

In weight and fat loss, there are no panaceas (nothing works for everyone). But the evidence shows that low-carb eating, overall, is a valid and generally effective strategy for weight loss. It should also be borne in mind, I think, that low-carb regimes have been found to lead to more favourable outcomes with regard to, say, the lowering of triglyceride, sugar and insulin levels.

References:

1. Sondike, S B et al., ‘Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents’, J Pediatr 2003; 142(3): 253-58

2. Brehm, B J et al., ‘A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women’, J Clin Endocrinol Metab 2003; 88: 1617-23

3. Foster, G D et al., ‘A randomized trial of a low-carbohydrate diet for obesity’, N Engl J Med 2003; 348: 2082-90

4. Yancy, W S Jr et al., ‘A low carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia. A randomized, controlled trial’, Ann Intern Med 2004; 140: 69-77

5. Stern, L et al., ‘The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial’, Ann Intern Med 2004; 140: 778–85

6. Gardner, C D et al., ‘Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women: The A TO Z Weight Loss Study: A Randomized Trial’, JAMA 2007; 297: 969-77

7. Shai, I et al., ‘Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet’, NEJM 2008; 359: 229-41

Low-GI/GL diets may help reduce risk of disease and death by quelling inflammation

Carbohydrates that tend to be disruptive for levels of sugar in the bloodstream (high glycaemic index carbs) can provoke disease-causing changes in the physiology and biochemistry in the body, including enhance inflammation (see here for more about this). The pro-inflammatory effect of high-GI carbs has important implications, because inflammation turns out to be a key underlying process in conditions such as cardiovascular disease (e.g. heart attack and stroke) and cancer.

Cardiovascular disease and cancer are but two conditions that have links with inflammation in the body. Others include infectious diseases (e.g. septicaemia, pneumonia, flu), diabetes, lung disease, gastrointestinal disease (e.g. stomach or duodenal ulceration) and kidney failure. Inflammation can cause debilitating disease and death too. Bearing in mind that high-GI carbs can increase inflammation, could they increase the risk of death from inflammatory conditions aside from cardiovascular disease and cancer?

That is essentially the question posed by a piece of research published this week in the American Journal of Clinical Nutrition [1]. In this study, 1490 postmenopausal women and 1245 men aged 49 or older were followed over a 13-year period. Women eating relatively high-GI diets, compared to those eating relatively low-GI diets, were found to be almost 3 times more likely to die from inflammatory diseases (excluding cardiovascular disease and cancer). This association was not found in men, however. There was no association in either men or women between dietary GI and risk of cardiovascular death either. Previous studies, however, have found that higher-GI diets are associated with a 20-100 per cent increased risk of cardiovascular disease (see here).

Why the association between higher-GI foods and increased risk of death from inflammatory disease in women but not in men? The authors point to previous research which demonstrates stronger links between GI and things like inflammation, excess weight, metabolic syndrome and type 2 diabetes in women than in men. They also point out evidence which showed generally higher ‘antioxidant status’ in men up to the age of 75, which might afford men greater protection against the pro-inflammatory nature of high-GI carbs.

My lasting impression from this study is that it’s perhaps a good idea to keep inflammation in check in the long term. A decent intake of omega-3 fats might be one approach here, but so is eating a diet of relatively low glycaemic index and load. One often-used marker for inflammation in the body is a substance known as ‘C-reactive protein’ or ‘CRP’ for short. The authors of the study discussed here cited evidence linking the consumption of low GI/GL diets with lower CRP levels in healthy overweight individuals [2] as well as in individuals with type 2 diabetes.

References:

1. Buyken AE, et al. Carbohydrate nutrition and inflammatory disease mortality in older adults. Am J Clin Nutr 23 June 2010 [epub ahead of print publication]

2. Pittas AG, et al. A low-glycemic load diet facilitates greater weight loss in overweight adults with high insulin secretion but not in overweight adults with low insulin secretion in the CALERIE Trial. Diabetes Care 2005;28:2939-41

3. Wolever TM, et al. The Canadian Trial of Carbohydrates in Diabetes (CCD), a 1-y controlled trial of low-glycemic-index dietary carbohydrate in type 2 diabetes: no effect on glycated hemoglobin but reduction in C-reactive protein. Am J Clin Nutr 2008;87:114-25

Snacking associated with improved weight control

Conventional wisdom often dictates that we should eat three meals a day with nothing in between. The idea here is that snacks just add to our calorie intake, and therefore can only contribute to our body weight. However, I find in practice that for successful weight management, more frequent feeding is required. Regular eating can, theoretically ‘stoke’ the metabolism, and may help temper insulin levels too [1,2] (and insulin is the chief hormone responsible for fat storage in the body).

The other thing, of course, is that regular eating can help stop the appetite running out of control. This is important because a rampant appetite can make it mightily difficult to make healthy food choices, both in terms of what and how much we eat. Put another way, snacking can make it much easier to eat healthily.

I was interested to read a study published this week which looked at the relationship between snacking and risk of being overweight [3]. The study, published on-line in the American Journal of Clinical Nutrition, found that more frequent snacking was associated with a lower risk of being overweight. Snacking was associated with a reduced risk of having excess weight around the middle too.

Now, so-called ‘epidemiological’ studies of this nature only really tell us about associations between things, and this study therefore does not necessarily indicate that snacking protects against unhealthy weight gain. It is possible, say, that individuals of healthy weight quite naturally feel less need to restrict their food intake and are more relaxed about eating snacks. Also, overweight individuals may tend to under-report any snacking they partake in.

However, it should not be forgotten that there are quite sound reasons for why snacking might genuinely help protect against weight gain (see above). Plus, there are other studies which support the notion that snacking is generally good where weight management is concerned. For example, in one study, the more regularly individuals te, the lower their body weight and fatness tended to be [4]. This association even remained after accounting for other factors that might help explain it, such as physical activity and overall food intake. In another study, individuals eating five or more times a day, compared to those eating three or fewer times each day, were half as likely to be overweight [5].

When it comes to what to snack on, I generally suggest nuts. Nuts are also a generally very nutritious food, and their consumption is associated with a reduced risk of chronic disease including heart disease. But one of nuts’ best features, I think, is their capacity to sate the appetite effectively. This contrasts with, say, fruit, which tends not to sate the appetite very well at all. The slow sugar-releasing and relatively protein-rich nature of nuts almost certainly contribute to their appetite sating properties.

Despite their ability to quell hunger effectively, nuts tend to have a reputation as a fattening food. Actually, though, the evidence suggests that nuts do not promote weight gain. Some evidence suggests they actually promote weight loss.

One reason for this is that when people eat more nuts, they often simply eat less of other foods. For more about this, see here.

References:

1. Jenkins, D J et al., ‘Nibbling versus gorging: advantages of increased meal frequency’, N Engl J Med 1989; 321(14): 929-34

2. Rashidi, M R, et al., ‘Effects of nibbling and gorging on lipid profiles, blood glucose and insulin levels in healthy subjects’, Saudi Med J 2003; 24(9): 945-48

3. Keast DR, et al. Snacking is associated with reduced risk of overweight and reduced abdominal obesity in adolescents: National Health and Nutrition Examination Survey (NHANES) 1999–2004. Am J Clin Nutr 16 June 2010 [epub ahead of print publication]

4. Ruidavets, J B et al., ‘Eating frequency and body fatness in middle-aged men’, Int J Obes Relat Metab Disord 2002; 26(11): 1476-83

5. Fabry, P et al., ‘The frequency of meals its relationship to overweight, hypercholesteremia, and decreased glucose-tolerance’, Lancet 1964; 2: 614-15

More evidence comes in that saturated fat does not cause heart disease

Back in April I wrote about my ‘love-hate relationship’ with dairy products. The love part of my relationship relates to the fact that many dairy products are rich in protein and low in carbohydrate, coupled with the fact that I actually like the taste of things like cream, yoghurt and cheese. The hate part of the relationship is based on some science and a lot of experience that leads me to believe that dairy products are quite-common triggers of food sensitivity reactions that can manifest as a variety of issues including sinus and nasal congestion, asthma and eczema. Actually, I personally had eczema for many years which appears to be rooted in a sensitivity to cow’s milk. You can read more about this here.

So, my issues with dairy products are not based in the usual concerns about saturated fat. I for a long time have not been concerned about saturated fat because, well, there really isn’t any evidence that this dietary component causes heart disease (or any other disease, for that matter). And fat does not appear to be explicitly fattening, either. So, when individuals do eat dairy products I never urge them to drink watery skimmed milk and joyless low-fat yoghurt. I eat yoghurt reasonably frequently (usually as part of my breakfast), and it’s a 10 per cent fat Greek yoghurt that is my usual default food.

When I express my views on the claim that low-fat airy products are somehow healthier than their full-fat versions the general reaction can perhaps be best described as a mixture of shock and relief. Shock from the fact that we have been so consistently misled regarding the role of saturated fat in health. Relief from the fact that watery milk and joyless yoghurt will no longer need to be endured.

This is the background to my interest in a recent study published on-line in the American Journal of Clinical Nutrition which assessed the relationship between diary fat and risk of heart attack [1]. Studies of this nature usually assess food intake through questionnaires. These are prone to inaccuracy. The authors of this study took a different tack: they measured the levels of two saturated fats specific to dairy products by the names of pentadecanoic acid and heptadecanoic acid.

In men, there was not statistically significant relation ship between dairy fat and risk of heart attack at all.

In women, the results indicated that, if anything, higher levels of dairy fat in the body (and therefore diet) are associated with a reduced risk of heart attack.

It should be noted that one of the eight authors of this study declared previously receiving speaking fees from the Swedish Dairy Association and the International Dairy Federation.

Notwithstanding this, the results of this study again support the idea that saturated fat does not cause heart disease. And the results also support the idea that there’s no need to eschew full-fat dairy products for the sake of our health.

References:

1. Warensjö E, et al. Biomarkers of milk fat and the risk of myocardial infarction in men and women: a prospective, matched case-control study. 19 May 2010 [epub ahead of print publication]