Research shows that protein-rich, low-carb diets are most effective for sating the appetite

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You don’t have to wait too long before reading some statistic or other that tells us about how rates of obesity are soaring left, right and centre. As ever, though, the advice to ‘eat less and exercise more’ remains the same. That’s a shame, seeing as there is abundant evidence that neither of these approaches is effective for the purposes of weight loss in the long term.

The reasons for the failure of traditional weight loss advice are complex, but have at least something to do with the fact that when people eat less they usually feel hungrier and this is a sensation that few will be able to tolerate in the long term. Plus, when people become more active they tend to be hungrier and also are generally compelled to eat more as a result Perhaps a better approach would be one which would allow individuals to be able to lose weight without being hungry.

Of course a lot of people have already discovered that a way to achieve this is to cut back on carbs. When someone embarks on the Atkins diet, for instance, they will almost always confess to feeling less hungry then the ordinarily do. I just found myself eating less� is a common cry from low-carbers.

One of the reasons that Atkins and diets like it tend to reduce hunger and food intake has to do with the fact that these diets are rich in protein. And calorie for calorie, protein has been found to sate the appetite more than either carbohydrate or fat. The mechanism behind the appetite sating power of protein was recently investigated in a study which is due to be published in the Journal of Clinical Endocrinology and Metabolism. The study, conducted at the University of Washington in Seattle, USA, involved the giving of beverages of different nutritional make-up to a group of 16 subjects. The beverages differed in terms of the relative amounts of protein, fat and carbohydrate they contained.

Before and after consuming the drinks, the subjects had blood drawn and this was analysed for levels of a hormone called ghrelin ” higher levels of which are known to stimulate the appetite. According to reports regarding this study, protein was found to be the best suppressor of ghrelin. It also, not surprisingly, was most effective in terms of sating the appetite.

I was also interest to read about the ghrelin response to carbohydrate. The reason being is that I’ve lost count of the number of people who find that eating a carbohydrate rich diet just fails to satisfy for long. It turns out that after consuming a carb-rich drink, the ghrelin response is suppressed at first. But then, apparently, ghrelin came back with a vengeance, and actually left individuals hungrier than before they had eaten.

This finding is utterly consistent with the experience that some many people have of eating a carb-rich meal which ‘hits the spot’, but only for a relatively short period of time compared to something ‘heavier’ in terms of protein content. There may of course be other mechanisms at play here, but this study does seem to provide a legitimate explanation for many people’s experiences in the real world.

As an addendum to this, I’d also like to discuss the results of a study published this month in the American Journal of Clinical Nutrition [1]. The study involved giving a group of obese men two different diets, each for a 4-week period. Both diets were reasonably rich in protein (30 per cent of calories). The diets different, though, in that one of them low-carb (4 per cent of calories) while the other was higher in carbs (35 per cent of calories). The men were allowed to eat as much of these diets as they liked.

Compared to when eating the higher carb diet, the low-carb diet led to:

1. Reduced hunger
2. Reduced caloric intake (an average of 167 calories less each day)
3. Improved weight loss (weight loss of 6.34 kg compared to 4.35 kg)

The level of carbohydrate restriction in the ‘low-carb’ group was considerable, and might be unsustainable in the long term. However, this study demonstrated very clearly that in a diet containing a decent amount of protein, eating more carb is less satisfying.

Take these two studies together and there is, I think, quite compelling reasons to believe that if individuals are going to eat less in a sustainable way (i.e. in a way that does not just make them hungry), then a protein rich, carb-controlled diet is generally the way to go. Mind you, as I alluded to above, countless individuals will attest to that fact as a result of their experiences in the real world.


1. Johnstone AM, et al. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr 2008 87: 44-55

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