Over at Body Recomposition, Lyle McDonald has written a great article which explores the question “are all calories created equal?”
Simply put, the debate comes down to this: all that matters is caloric balance (calories in versus calories out) or do the source of those calories matter?
Does eating 100 calories of fat have the same impact on weight as 100 calories of protein or fat? Certainly diets with different mixes of these elements report different degrees of success – namely that the success of low carb diets tend to suggest that carbs are the heavier calories. But perhaps this is a misinterpretation of the data…
[where calories are strictly controlled]… given adequate protein, it seems to matter very little what diet is chosen. From a weight or bodyfat standpoint, high carb should be as good as low-carb.
But as Lyle goes on to explain, the sad truth is that the assumption that the calories can be controlled is virtually impossible in the real world and that is where the different foods show their true impact on our bodies…
Put a little bit differently, it might very well be possible to lose all the weight/fat you wanted on a calorie controlled junk-food diet with some high quality protein source. The problem that would probably arise is that most people wouldn’t be able to control their hunger or appetite on such a diet and they’d probably end up eating more in the long run. In eating more, they’d either lose less weight/fat or even gain it. Even if a given dietary approach appears optimal for some reason, if you can’t control your caloric intake, and end up eating more because of it, it won’t produce results. (…)
As well, the source of calories can affect other aspects of physiology beyond body composition. Health, energy levels, hunger/appetite and all the rest interact here. So while a calorie controlled diet of jelly beans, butter and protein powder might very well work to lose weight/fat, it probably wouldn’t be as healthy compared to a diet of low GI carbohydrates, healthier oils and lean protein sources.
So the bottom line is that the question is flawed. Calories are more or less calories… but different foods will have differing impacts on your tendancy to eat and lose weight – both in the short and long term.
Understand me here? Issues such as hunger control, long-term adherence, individual variance, athletic performance, and a few others all go into the determination of what food might or might not be a better choice under a given set of circumstances. So while a calorie might be more or less a calorie under somewhat artificial conditions (where calories are or can be strictly controlled), it’s a little more complex than that in the real world.