SmarterFitter

Ah, Sunday morning, an hour stroll around our local park first thing. Work up a bit of an appetite during the walk. Pick up a paper on the way home... something to read over breakfast. Exercise and food... mmm.

So, reading the Observer this morning I came across Gary Taubes' nice contrarian article about exercise and weight loss. According to the article there isn't any research linking exercise with weight loss and that basically all exercise does is make you hungry so you eat more. Now, I reckon the guy might be building up a bit of straw man here because I think most people understand that exercise alone isn't going to do you much good unless you use it to create a calorie deficit and to do that you do need to think about what you're eating even when you're exercising.

What did get me thinking was his argument that the conventional model that treats the body as a "thermodynamic blackbox" (or, a calories-in, calories-out balance sheet) is naive and takes no account of how physiology and hormone levels effect fat loss/gain. In fact, it is the hormone insulin, in conjunction with an enzyme called lipoprotein lipase (LPL) which determines whether we store fuel (glucose and fatty acids) as fat or burn them for energy.

If it's biology, and not a lack of willpower, that explains why exercise fails so many of us as a weight-loss tool, then we can still find reason for optimism. Since insulin is the primary hormone affecting the activity of LPL on our cells, it's not surprising that insulin is the primary regulator of how fat we get. 'Fat is mobilised [from fat tissue] when insulin secretion diminishes,' the American Medical Association Council on Foods and Nutrition explained back in 1974, before this fact, too, was deemed irrelevant to the question of why we gain weight or the means to lose it. Because insulin determines fat accumulation, it's quite possible that we get fat not because we eat too much or exercise too little, but because we secrete too much insulin or because our insulin levels remain elevated far longer than might be ideal.

Simple carbohydrates increase insulin levels. Fewer slices of toast and jam with breakfast then. And more poached eggs? So, not all calories are created equal and eating slow carbs matters [not recommending that diet, just think it is an interesting thought experiment].

There is no doubt that exercise has health benefits but it isn't going to get you lean by itself. Think about the type of calories you're getting: percentages of fat, protein, carbs and try to keep your eating in check when you are exercising.

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