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Does Lack of Protein In Your Diet Drive Weight Gain?



sharma-obesity-proteins-picture1One of the many competing beliefs about how our diet may affect our weight is the “protein leverage hypothesis”.

Simply stated, the notion is that given the importance of protein for the maintenance and functioning of virtually every organ system in our body, we are driven to continue eating till we meet our protein needs – if that means eating extra calories – so be it.

According to this hypothesis, much of obesity related to processed foods has to do with their relative low protein content, which forces us to eat more them in order to maintain the right level of protein intake.

Now a direct test of this hypothesis by Eveline Martens from Maastrecht University, published in the American Journal of Nutriotion, fails to find evidence to support this idea.

This randomized cross-over 12-day study examined the effect of three different diets (5%, 15% or 30% of energy from beef protein) on ad libitum energy intake, body weight changes, appetite profile, and nitrogen balance in around 60 individuals randomized in crossover fashion.

Energy intake was significantly lower in the 30En%-protein condition compared to the 5en% and 15en% condition.

In line with this, hungerand desire to eat ratings were higher and fullness ratings were lower in the 5En%-protein condition than in the 15En%-protein and 30En%-protein conditions.

Although Nitrogen balance was positive in the 15En%- and 30En%-protein conditions, the subjects managed to maintain protein balance on the 5en% diet.

Thus, the study showed that higher levels of protein intake reduce ad libidum energy in take (at least in the short term) whereas restricting protein intake may not necessarily lead to an increase in caloric consumption.

Obviously, enthusiastic supporters of the protein leverage hypothesis will hurry to point out (as do the authors), that the subjects managed to stay in nitrogen balance on the low-protein diet and therefore did not have to increase their energy intake to meet protein demands – this may be different in a longer-term study where eventually lack of protein intake may well influence eating behaviour.

So what this means for obesity management I have no clue. We already know that higher protein diets may be easier to follow and lead to a lower ad libitum calorie intake that low-fat or low-carb diets (at least for some people).

Will cutting your protein intake make you eat more? I’m still waiting for hard evidence on this.

@DrSharma
Edmonton, AB

ResearchBlogging.orgMartens EA, Tan SY, Dunlop MV, Mattes RD, & Westerterp-Plantenga MS (2014). Protein leverage effects of beef protein on energy intake in humans. The American journal of clinical nutrition PMID: 24760974

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3 Comments

  1. It would be nice to see a photo of “protein” that included more plant proteins (I love the circle of beans that looks like an afterthought!). I contend that it isn’t the lack of protein in junk food that makes people overeat, but the lack of vitamins, minerals and micronutrients. And I didn’t think many people in the first world were suffering from an underconsumption of protein, whether or not their diet contains a lot of junk food!

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  2. Interesting, as always, Dr. Sharma.
    What are your thoughts then on low carb diets? (Atkins, Dr. Bernstein, etc).
    I personally think that 20-30 g of CHO/day is way too low to sustain long term, but many patients (and health care professionals I know) still advocate it. And though I’ve never heard them specifically reference the protein leverage hypothesis, many of their arguments for high protein, low carb diets seem to boil down to this idea.

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  3. First, for myself, cutting good quality protein will cause me to crave, and will result in higher quantities of food intake. It is not just a quantity but also quality of protein issue. Processed meats are not suitable for me, they leave me hungry, as does chicken and pork. Fat beef is good as is fat fish. Any food that does not satiate is not a suitable weight loss food. Sugar, fructose, wheat, grains in general are, for me, and appetite stimulus.

    About 20 g of carbs is easy to do if I cook all meals, but not if the food prep is not in my control. Typically 50 gm is more reasonable. To sustain low carb, we need to increase the saturated fats, not omega 6 or dairy fats, which most of the medical profession and “dieters” panic over. The main thing that must happen is we need to get our insulin down to lose weight, without excessive calories.

    When we are losing weight, we do not know where the fat or protein that we are actually using is coming from, so nitrogen balance is misleading short term. The advantage of high protein is less muscle loss as well as reduced hunger, but the reduced hunger is likely the associated fats.

    The difficulty in low carb is not physical in my case, but all the pushy people offering ignorant opinions about low carb, and all the added sugar. Even a typical fast food hamburger without bun has fructose used as a browning agent. Enough that I can taste it.

    Addressing and understanding the reasons that I overate in the first place, along with understanding food and the actual physiological requirements has helped. Typical media and even some medical persons are misinformed.

    But what do I know? maintaining -50+ kg for 5 years now.

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