Review confirms superiority of low-carb over low-fat for weight loss and cardiovascular disease risk factors

In the World of nutrition, not everyone shares the same opinion (obviously). And perhaps the most stark and common example of this concerns the relative amounts of carbohydrate and fat we should have in our diets. The conventional view is that the diet should be, generally speaking, low in fat and high in carb. Fat, we are told, makes us fat, so eating less of it is the sure-fire way to keep lean and healthy. On the other hand, some argue that it’s not too much fat that makes but, but too much carb. Such individuals will advocate a low-carb diet, which may (but may not) end up being quite rich in fat.

Variously on this site I have referred to studies which, overall, show that low-carb diets outshine low-fat ones in the weight loss stakes. I’m not aware of one single study, as it happens, which found a low-fat diet to be superior in this respect. Those that cling to the idea that low-fat is the way to go, will very often resort to claiming that low-carb diets are unhealthy, often on the basis that their sometimes high fat content will put people at risk of cardiovascular diseases such as heart disease and stroke. I have to say I’m unmoved by this argument for two main reasons.

Firstly, there really isn’t very much evidence linking supposedly unhealthy saturated fat (found mainly in meat, eggs and dairy products in the diet) and increased risk of cardiovascular disease. Neither is there much (if any) good evidence that eating less saturated fat has broad benefits for health.

But my other major issue with the argument that low-carb diets are bad for the heart and circulatory system is that studies have found that such diets generally lead to improvements in biochemical markers of cardiovascular disease compared to low-fat diets. Many studies, for instance, have found that lower-carb diets have led to changes in blood fat levels that would be expected to lead to a reduction in cardiovascular disease risk.

I was interested to read of a study published very recently which sought to review the evidence in the area [1]. Thirteen studies in which low-carb diet were pitted against low-fat ones were included in the review, and each of these lasted at least 6 months. One limitation of the study was that the design of the low-carb diets in the individual studies sometimes allowed reintroduction of significant amounts of carbohydrate.

Despite this, the results showed that compared to the low-fat diets, the low carb ones had generally favourable outcomes. These included:

Significantly more weight loss at 6 and 12 months (about 4 and 1 kg respectively)

Significantly lower triglyceride levels

Significantly higher ‘healthy’ HDL-cholesterol levels

The low-carb diets had lower attrition rates too, suggesting that individuals have a harder time sticking to a low-fat diet compared to one that is carb-controlled. This is important, seeing as compliance is important if the benefits of any diet are to be sustained.

This review does a good job of assessing the relative benefits of lower-carb and low-fat eating. And it shows, once again, that as a general rule, the former is preferable for the purposes of weight loss and bring superior benefits in terms of cardiovascular risk factors too.

References:

1. Hession M, et al.Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities. Obes Rev. 2008 Aug 11. [Epub ahead of print]

14 Responses to Review confirms superiority of low-carb over low-fat for weight loss and cardiovascular disease risk factors

  1. Catherine 20 August 2008 at 1:39 pm #

    Since listening to you talk in Claremont, Cape Town 30 June, having read The True You Diet and having had the evil Mirena IUD removed in April, I have lost centimetres from my middle that I thought I would not be able to. Plus I have lost 2.5kgs without much effort at all, even though my exercise regime is not what it was. I am age 45 now and felt doomed to a thicker middle, which I knew was not the real me.

    No-one told me that, while the Mirena does not directly cause you to gain weight, it certainly does increase your appetite. Over a three year period WITH regular exercise, eating a low fat diet (yes!) I managed to gain about 10 kgs, I have never had a problem with my weight before! I am just over 5′ so any amount of weight gain shows dramatically on me, imagine 10 kgs?! I would think to myself ‘what more can I do if fat free is not working?’ I was stumped plus I had reflected on my carefree avo days and was confused about what was being told to me about fat content yet I had experienced the opposite.

    I grew up in Durban where avos were in abundance in our garden, and peanut butter was the other staple. None of us ever gained weight and we ate copious amounts of the above! So, I have reintroduced meat into my diet (106 is my score, on the cusp of Hunter) in moderation as I love vegetarian food as well, I have relaxed on skim milk and now use low fat (don’t like the creamy feel left by full-cream and i don’t have issues with milk), low fat yoghurt tastes so much better than fat free, i have butter with my veg or olive oil and guess what? I am really enjoying my food even more.

    I do your breakfast and eat eggs more. In time I will have my cholesterol checked, it has always been elevated, family history but I do think it is largely stress.

    So overall my sense of well-being, my sense of self is improving day by day. I don’t feel guilty about having a really good cup of coffee a day, I love it! I also find I have had chocolate (only 70% or darker) in my cupboard for months, i do love the oiliness and texture of 80%.

    There you have it, my input and feedback for you.

    Catherine

  2. teddy 20 August 2008 at 2:47 pm #

    Essentially, the key to losing weight is reducing calorie intake. No matter what you eat, if you cut calories consistently, you will shed pounds. The important question is: Can you—or should you—sustain the diet you are on forever? If you have risk factors for heart disease, you probably should not eat a high-fat diet for very long. If you stick to a very low-fat diet, you may find it very difficult to eat out!

    If you have to lose 10 pounds fast due to an obesity related disease and your doctor approves, you can lose it quickly on an Atkins type diet. But for long term success, the best diet is a balanced one that you can follow for life. Reduce total calories, use fats sparingly and include many types and colors of vegetables and fruits in small quantities throughout the week. Limit treats to a small amount rarely. And remember that the more calories you burn through exercise, the easier it will be to manage your weight.

  3. Neil 20 August 2008 at 9:42 pm #

    teddy, if you use fats sparingly and have fruit and veg in small quantities, where are the calories going to come from? If you’re trying to reduce calories permanently, then what you have suggested seems more a semi starvation diet, and not possible to adhere to due to hunger.
    I used to think a ‘balanced’ diet was the ideal, until I read up on nutrition and realised that ‘balanced’ stood for ‘everything in moderation’ as my Mother In Law would say. Not scientific but a cosy appeal to ‘common sense’

  4. BQ 21 August 2008 at 11:54 am #

    Dear John,

    Just a thought i want your input on..

    I dont believe in low fat or low carb.. i have tried both and none have worked long term because one tends to crave the limited one..

    i have stumbled across something called “the warrior diet”
    http://www.warriordiet.com

    which basically means that u graze on fruit and veggies throughout the day then “feast” on one meal of your choice without restriction..

    what are your thoughts on this?

  5. Hilda 22 August 2008 at 7:25 pm #

    Teddy . Where is the evidence for what you say? If you consistently cut calories your body will adapt, your thyroid hormones will reduce to conserve energy and in the long run you will get fatter and fatter. Calories do not matter as much as you say they do. Carbs cause problems as we are not meant to eat sugar etc.

  6. Tiggy 22 August 2008 at 11:32 pm #

    RE the ‘warrior diet’. I only have one meal a day in the early evening and maybe an apple earlier in the day, but I don’t lose weight even though my food is low GI and low fat and fairly low in carbs and I go to the gym at least four times a week.

    There have been three occasions where I’ve really lost weight:

    1) When I didn’t eat at all for about five days.

    2) When I was very ill in India.

    3) When I lived mainly on gin and tonic for a month – many years ago.

  7. Stefan 23 August 2008 at 5:38 am #

    Teddy: the calories in calories out doesn’t work. If you try to eat less and expend more, your body will adapt and consume the protein of your muscle tissues for energy, while leaving the fat intact.
    The key is to keep your insulin low. Insulin is the anabolic hormone which builds the fat deposits. The other key is to mobilize fat via weight training. Low insulin means a low carb diet – same hunter-gatherer diet and effort style which built the human body through the evolutionary phase before the invention of agriculture a few thousand years ago.

  8. Hilda 24 August 2008 at 12:31 am #

    Tiggy. If you are being serious and just having ebery one on yoiur body has probably adapted to your low food intake. Have your thyroid checked.

  9. Tiggy 24 August 2008 at 10:14 pm #

    Thanks. I’m going to have it checked again, but I had it checked a few years ago and the doctor said it was okay. I don’t think they do anything about it unless it’s very bad. I’m thinking of having a second private test done if I get nowhere with the NHS one. There is a different sort of test you can have.

  10. teddy 25 August 2008 at 4:27 pm #

    “Teddy: the calories in calories out doesn’t work. If you try to eat less and expend more, your body will adapt and consume the protein of your muscle tissues for energy, while leaving the fat intact.”

    —–
    To say that “the calories in calories out doesn’t work” is incorrect. To lose weight by balancing energy expenditure with energy release would break fundemental laws of thermodynamics. Although if you can propose a mechanism by which you think it is possible, go for it!
    —-
    Usual metabolic pathways preferentially burn fat over protein; of course this is not to say the body can use protein as a source of fuel: it does so continually in small amounts and when other sources of fuel are running out.
    —-

    I think the things to bear in mind is that for weight loss, carefeul management of calorie intake *is* important. The approaches I advocate are:

    *reduction in calories consumed combined with moderate exercise

    *a diet higher in protein and lower in carbohydrate – this approach works well becuase of the satiating affects of the protein, indeed, the reason why high protein diets are so effective is because they all reduce the total number of calories an individual consumes. Having said this, beware that you do not substitute-in too much saturated fat.

    Hope this clears a few things up!

  11. Becky Wells 25 August 2008 at 5:27 pm #

    After all the discussion and JB’s blog, I’m very interested in reducing my carbs as much as I can in order to lose weight and keep lean.As a post menapausal woman, I know that it will be harder for me to shift extra pounds. I’m the main cook for a family with two manually labouring men, so I need to be subtle about this. They do probably need more carbs than I do because it would be difficult to get the calories they need otherwise. I have stopped eating the obvious – spuds, pasta, bread and anything sweet such as cake, biscuits and sweets and am filling the gap with vegetables, fruit and salads. Has anyone any suggestions as to what else I can do or of any helpful books?

  12. Kirsty 26 August 2008 at 8:09 pm #

    BQ – the Warrior Diet is also low-carb / paleo kind of diet, the meal at night should be paleo.

    Becky – I did what you did but also found that if I wait until I’m hungry to eat, I don’t eat until about mid-afternoon when I’d have something small, like a bowl of soup (not low fat though). Then I’d have dinner later, like you, substituting more veggies for the starches. Because I had cut out the carbs, I didn’t have low blood sugar or sugar spikes, just normal hunger. I found the Warrior Diet because I was a bit worried about not eating during the day but now I just go with my appetite. I eat a lot less than I used to. I also query whether the 2000 calorie a day recommendation for women is too much, especially post menopause.

  13. Jackie Bushell 26 August 2008 at 9:42 pm #

    Becky

    There are some free resources such as menu plans which you might find useful on my website.

    Teddy

    PLEASE read Gary Taubes’ book ‘The Diet Delusion’ . He explains much more eloquently than I ever could why ‘calories in calories out’ is incorrect in as far as the phrase is usually used, and that this does not contravene the laws of thermodynamics .

    Jackie

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    [...] Review confirms superiority of low-carb over low-fat for weight loss and cardiovascular disease risk…In the World of nutrition, not everyone shares the same opinion (obviously). And perhaps the most stark and common example of this concerns the relative amounts of carbohydrate and fat we should have in our diets. The conventional view is that the diet should be, generally speaking, low in fat and high in carb. Fat, [...] [...]

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