Where weight loss is concerned, could it be that it’s more than calories that count?

I was in a meeting today, and the subject of weight loss came up. As some of you may know, I have previously written about how exercise tends not to be particularly effective for those wishing to shed pounds.

I made the point that those wanting to lose weight would do better to, among other things, eat a diet that is rich in foods that tend to sate the appetite quite effectively. There is some evidence that in this respect, protein is king.

One of the other usual keys to successful weight loss is to concentrate on eating a diet based on foods that tend not be stored as fat (avoiding the over-consumption of many carbs including bread, potatoes, rice, pasta and breakfast cereals is key here). What this amounts too, in effect, is a diet that is rich in protein and low in carb.

Such a diet is not for everyone, but I have to say over the years I’ve found it one of the most effective strategies for individuals wanting to improve their health, weight or wellbeing. I don’t know how many people I’ve had personal dealings with who say they have been freed from a life of yo-yo dieting and semi-starvation simply by eating a relatively protein-rich (and lower carb) diet.

There’s a growing number of studies that support this way of eating for successful weight control, and one example is a study published in January in the American Journal of Clinical Nutrition [1]. This study took a group of obese women (average age 49) and assigned them to one of two diets: high protein or high carbohydrate, for a period of 64 weeks (12 weeks of supposedly quite strict dieting followed by a year of less severe restriction). Both groups lost weight, but there was no significant difference between the two groups.

There’s one thing to instruct people what to eat, whether they do it or not is another matter. So, the researchers involved in this study attempted to check ‘compliance’ using a urinary test which gives an indication of the amount of protein the women ate. Because there was no significant difference in this measurement between the groups, the researchers concluded that compliance was likely to have been ‘poor’.

So, what the researchers did next was to get the dietary records of the women and calculate from them what they actually ate, including their protein intake. And that’s when things got more interesting. What they found was this:

The more protein the women ate, the more weight they lost.

The average weight loss for women who reported eating a high protein diet was 6.5 kg. In comparison, those eating a lower protein diet lost an average of 3.4 kg. Despite the fact that the protein-rich diet eaters lost almost twice as much weight as their lower-protein eating counterparts, this difference was not found to be ‘statistically significant’. This might have had something to do with the fact that the numbers of women who had their diets analysed was small (a total of 52). Despite this, the group eating a protein-rich diet were found to lose significantly more ‘peripheral’ fat (2.4 kg on average compared with 0.9 kg).

One reason for these generally improved outcomes from eating a protein-rich diet might be related to protein’s appetite-sating ability. However, when I checked the calorie intakes, I was surprised to find that the higher protein group ate significantly more calories (an average of about 170 calories more a day).

This finding first of all flies in the face of the idea that people eating a protein rich diet tend to eat less. And I have no explanation for it. Perhaps it had something to do with the fact the gathering data on what people eat is fraught with difficulty. However, what about if we take these results at face value? Let’s assume, for a moment, that the high-protein group ate more but lost more weight.

One explanation here is that the high-protein eaters were more active. Unfortunately, the study provides no data on activity levels. In view of the fact we have no evidence to the contrary, I’m tempted to assume that activity levels were the same.

Some would say this can’t be so, because it contravenes what is known as the ’1st law of thermodynamics’ (which basically states that energy can’t be created or destroyed – only its form can be changed).

However, remember that one way to lose weight is to eat a diet that tends not to get stored as fat. The fat storage hormone in the body is insulin, which is secreted primarily in response to carbohydrate consumption. As expected, the protein-rich dieters actually ate generally less carbohydrate (and more fat, by the way) than their lower-protein eating counterparts.

So, it might have been that the higher protein, lower carb diet resulted in less fat deposition in the body. But if that’s the case, where might the energy that didn’t get stored as fat go?

Well, one thing we know is that when people eat more protein it increases what is known as ‘protein turnover’ in the body [2]. And there’s also evidence that when protein turnover increases, so does the body’s metabolic rate [3].

In short, there is at least some evidence suggests that when people eat more protein and less carb, less of what they eat is stored as fat, and the energy that appears to go ‘missing’ is simply burned by a more ‘efficient’ metabolism. When it comes to weight control, it might be that it’s more than just calories that count.

References:

1. Clifton PM, et al. Long-term effects of a high-protein weight-loss diet. American Journal of Clinical Nutrition 2008;87(1):23-29

2. PJ Garlick, et al. Influence of dietary protein intake on whole-body protein turnover in humans. Diabetes Care 1991;14(12):1189-1198

3. Welle S, et al. Relationship of resting metabolic rate to body composition and protein turnover. Am J Physiol 1990;258(6 Pt 1):E990-8

20 Responses to Where weight loss is concerned, could it be that it’s more than calories that count?

  1. Sue 29 February 2008 at 10:31 am #

    Your not getting into the tricky subject of metabolic advantage of low-carb diets? There are two camps on the subject – those that don’t believe in the metabolic advantage and think its just to do with calories in the end and those that do.

  2. Dr John Briffa 29 February 2008 at 11:56 am #

    “Your not getting into the tricky subject of metabolic advantage of low-carb diets?”

    I think I am! This is one area where I’m somewhat ‘on the fence’. From what I know, there are theoretical mechanisms that support the metabolic advantage concept, but I don’t think I’ve seen any particularly definitive evidence of it clinically. If anyone has what they feel is good evidence either way, then please do share.

  3. Liz Clarke 29 February 2008 at 1:00 pm #

    Could fluid retention be one of the reasons for the difference in weight loss?

  4. Anne 29 February 2008 at 2:12 pm #

    Last year I was diagnosed with diabetes, type 2, but I am not the typical profile as I am slim and not insulin resistant. I soon found when I got my blood glucose meter that it was carbohydrates which raised my blood sugars so I reduced my carbs to just leafy green veggies, avocados and the bits that are in nuts….meat and fish have no carbs. I was already on a grain and dairy free diet as I am Paleo. In other words I went on a very low carbohydrate, high protein and high fat/oil diet. I was eating well in excess of 2,000 calories per day yet over the course of six months I steadily lost weight at the rate of 1/2 kilo per month, weight I could ill afford to lose as I was already verging on underweight. I was drinking olive and rapeseed oil by the spoonful to give myself extra calories so that I wouldn’t lose weight but it didn’t help at all ! In the end my endocrinologist prescribed me repaglinide so that I could eat some carbohydrate without raising my blood glucose, just some fruit with my main meal that’s all it needed, and that small increase in carbohydrates stemmed the weight loss.

    So for me I am living proof that if you cut carbs very low and raise protein and fat you can eat tons and lose weight….even if you don’t want to !

    Anne

  5. Paul Anderson 29 February 2008 at 2:48 pm #

    When all is said and done, what most people worry about where weight is concerned is the ditribution and quantity of body fat. Not many people would be worried by having a BMI of 28 if they were lean and toned. On the other hand you could have a BMI of 25 and have a paunch, and weak bones.

    For people who are overweight (with fat), something has gone awry with their fat metabolism. They gain body fat too readily and they lose it with great difficulty. Their body spends too much time making fat and not enough using it.

    Is it too simple to say that carbs generate insulin generates body fat. The double whammy is that this same insulin prevents fat being released from adipose stores, resulting in increased appetite, more carbs, more insulin and more fat, and so on.

    In nature fruits are seasonal, and available generally for a short period of time. They were also less sweet than today’s selectively bred varieties. Today fruit is available all year round, alongside fruit juice, sucrose, confectionery and a whole host of processed carbs and corn fructose rich carbonated beverages. Over consumption of these carbs can only have one result – weight gain.

    If you have gained weight it is obvious that you are depositing more fat than the body is utilising for energy. The best way to make this energy store accessible to the body is to reduce circulating insulin levels – which you can only do if you reduce consumption of carbs to a level that unlocks the door to the adipose tissue. I do not see how a high carb diet can accomplish this for an overweight person.

    I would suggest that each person needs to eat a diet that best suits their metabolism. For some that will be lower carb than others. A low carb diet has the advantage of being nutrient dense, high in fat soluable vitamins and appears to be less stressful to the body than a high carb, low fat diet. I suspect it more satiating not because of its high protein content but because the lower circulating levels of insulin mean that the body, at the cellular level, has ready access to free fatty acids as an energy source. You don’t feel hungry because the body has adequate access to amino acids and fat. When the body shuts down the supply of fat, hunger results.

    Thus far it has proved difficult to establish that low carb diets have a metabolic advantage.

    But it is well known that the best way to fatten cattle to to feed them up on corn based products. The fois grois example being an extreme example of a high carb diet- not apparently good for liver. It seems strange that a complex carb (high glucose) based diet is prescribed for weight loss in humans, with, it has to be said, very little evidence to suggest that it works or results in good health. On the other hand its difficult to imagine someone becoming obese on an all meat diet, supplemented with a few vegetables.

    Paul.

  6. Jordane Galasso 29 February 2008 at 3:09 pm #

    I would like to know what could be the long term problems connected with high proteins diets (impact on kidneys and other organs). Many thanks. Best regards

  7. Cali Bird 29 February 2008 at 4:11 pm #

    How should one replace the carbs in a meal? I get hungary without carbs especially if I don’t have any at lunchtime.

  8. rm 29 February 2008 at 5:05 pm #

    Hey, Doctor, help a vegetarian out. most of the sources of protein we eat have lots of carbs. Beans, nuts, seeds. What so you recommend for those of us who don’t want to be part of the animal cruelty or ecological destruction that the meat industry helps to foster. rm ps email still wrong.

  9. Neil 29 February 2008 at 6:20 pm #

    If the ‘a calorie is a calorie’ argument is correct, then the body would have to metabolise fat protein and carbohydrate via identical chemical processes. Which as we know, is not the case.

    Don’t forget that futile cycling uses up energy, for example, in keeping body temperature constant whilst we are idle. Sleeping apparently burns up around 60 calories an hour. Some of our food intake is used up in this way, and I’m sure there are significant differences between individuals.

    By the by, I am currently ploughing through Gary Taubes book, and he goes into this area in great detail.

  10. Liz 29 February 2008 at 7:31 pm #

    I think we need to determine what we mean by “high” protein or “low” carb. When I put someone on a weight loss diet I put them on a lower carb diet than they had before because they will tend to be eating less starchy carb. But I allow unlimited veg and some fruit – when you do the dietary analysis there is still plenty of carb in the diet. It is probably not as insulin inducing so lipolysis is more likely.

    As for protein, I encourage people to eat protein with every meal and a small protein snack between meals but these are not large portions of protein at any one time. Overall I suspect they do eat more protein than the minimum I recommend but that is balanced by a high amount of vegetable carbohydrate. I also suspect that they naturally adjust this diet to have the amount of protein that suits their palate. And one of the secrets of long term weight loss is to have a diet that suits your tastes so that you can eat this way forever.

    The feedback I get is that they don’t feel hungry and they are eating a lot of food. Weight loss is a small amount each week but it is fat, not muscle. And the type 2 diabetics seem to thrive on this approach.

    The question of what to do if on a vegetarian diet is more tricky. Balancing legumes and grains does increase the carbs – the only way to control it is to have wholegrain everything and possibly use vegetarian protein supplements as a protein “top-up”.

  11. Tiggy 29 February 2008 at 10:54 pm #

    I tried to eat only a low amount of carbs, but ended up feeling very tired all the time.

    I find it very hard to lose weight, but I definitely lose more when I exercise several times a week, usually 4 or more in my case. On days when I don’t exercise I tend to be cleaning for 3 or more hours at a fairly fast rate.

    Isn’t a drawback with a lot of protein that it can worsen inflammation through purines, or is that just in meat?

  12. Avalo 1 March 2008 at 3:47 pm #

    Discussions in nutrition are always difficult because most terms are ill defined and the systems are very complex. Thus, it gets very confusing. A low carb diet to one person is a very low carb diet for another. While metabolic advantage could come from hunger as Paul Anderson says, it could also come from gluconeogenesis or both or maybe something else. Of course, to measure either advantage is near impossible because of the complexity of the system. Even so, here’s my pitch for gluconeogenesis.

    If you go to the url listed at the bottom of the post, you will see the chemical path way of how the body makes glucose out of protein, which is what gluconeogenesis is. Under the energy catagory, they show that it takes 62kJ of energy per quantity of protein to make glucose. So, in summary, the body must consume energy to convert protein to glucose.

    The brain needs a certain amount of glucose every day. If a person is starving or semi-starving, (There we go again with the lose terms.) the body will use gluconeogenesis to produce the needed glucose. The same is true on a low carb diet. However, the difference between a starvation and a low carb diet is that the protein comes from the body in a starvation diet and from food in the low carb way of eating.

    So, to supply the brain with its required glucose, the body consumes 62kJ of energy per mole of glucose to get the required glucose from protein. Thus, gluconeogenesis is at least one source of the metabolic advantage of low carb diets.

    http://www.wiley.com/legacy/college/boyer/0470003790/animations/gluconeogenesis/gluconeogenesis.htm

  13. Hilda 1 March 2008 at 6:51 pm #

    rm Whey protein powder (Solgar) is good for a vegetarian as is quinoa, cottage cheese, and eggs.

  14. Sue 2 March 2008 at 2:26 am #

    Tiggy,
    “I tried to eat only a low amount of carbs, but ended up feeling very tired all the time”.

    You need to give your body time to adjust to a low carb diet as those tired feelings plus headaches etc usually occur as the body is switching over to burning fat for fuel. It may suit you to cut your carbs slowly not all at once as you are very active.

    “Isn’t a drawback with a lot of protein that it can worsen inflammation through purines, or is that just in meat?”

    Loren Cordain wrote in one of his newlsetters that in 2000 there was a study done on gout putting patients on a high protein, low glycemic load diet which resulted in 7 out of 12 patients with serum uric acid concentrations normalised and significantly reduced gout attacks. The authors concluded that the current dietary recommendations (low purine diets) for gout may need re-evaluation.
    Cordain – “It has been known for almost 40 years that
    fructose ingestion or infusions result in hyperuricemia (elevated blood uric acid levels).”

  15. Sue 2 March 2008 at 2:27 am #

    Sugar and grains are very inflammatory.

  16. Lindsay 3 March 2008 at 9:34 am #

    On a low carbohydrate regime should one restrict the amount of fruit one eats?

  17. Zilla Kent 3 March 2008 at 5:33 pm #

    Dr Briffa’s theorises that one part of a possible explanation for loss of more ‘peripheral fat’ in the dieters eating higher-protein but surprisingly more calories, might be because the foods they were eating caused less of the major fat storage hormone insulin to be released but this seems to confuse my lay-understanding of ‘peripheral fat’ and ‘visceral fat’.
    Visceral fat seems to be the type of fat that occurs around the abdomen and the type of fat most susceptible to gluts or shortfalls in insulin, peripheral fat which, i understand, is around the limbs, is both more harmless and less insulin-reactive. Surely if the insulin theory were to stand to reason the high-protein dieters would have lost more visceral fat?

    On a separate note – if Paul Anderson and Avalo reads this post please make contact – I am a writer with a great interest in this subject and was interested by your posts (zillakent@gmail.com )

  18. Neil 4 March 2008 at 6:47 pm #

    Lindsay, use this site to look up the carb content of the fruit you eat. Some fruits are more carb heavy than others. “Low” means different things to different people

    http://www.carb-counter.org/

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