A Calorie Isn’t a Calorie(?)

Ever since Nicholas Clement defined the calorie as a unit of heat back in the 19th century, we’ve used it as a measure for the energy available to our bodies in the food we eat. The so-called “kilogram calorie” (or kilocalorie), which you see on nutritional labels, equates to the energy needed to raise the temperature of one kilogram of water by one degree Celsius.

These capital-C Calories serve as an approximation for the amount of energy we take in from our food, as well as the amount of energy we expend over the course of our day, through a combination of essential life-processes and any additional physical or mental activity we add on top of the baseline.

Later on in the 19th century, chemist Wilbur Atwater used oxidation reactions to test the energy content of various nutrients, inclusive of corrections for rates of digestion and the production of urea. Atwater’s values, roughly 4 calories per gram for protein and carbs and 9 kcals/gram for fats, remain in use today.

Lately, however, there’s been a trend towards rejecting this model. Not only are calories thought to be insufficient — or outright irrelevant — in explaining the continuing rise in obesity, but the deeper reason is that “a calorie isn’t a calorie”.

Keep on reading &rarrow;A Calorie Isn’t a Calorie(?)

Interval Training, HIIT, and Tempo Training for Fat Loss

As I mentioned in the last post on the role of anaerobic metabolism in fat-loss training, you’re definitely better off doing some kind of activity that’s more intense than light jogging on the treadmill for miles at a stretch. That is, if you’re specifically trying to improve body composition. If you’re training for a race or something like that, it’s a different matter.

Keep on reading &rarrow;Interval Training, HIIT, and Tempo Training for Fat Loss

Anaerobic Exercise, EPOC, and Fat Loss

I was recently asked about the role of anaerobic metabolism in fat loss, and I figured that’s as good a topic as any to talk about.

For those unaware, your body has two basic ways of providing energy to your cells – one is oxygen-dependent, while the other can occur without oxygen. We know these are aerobic and anaerobic metabolism, respectively. We can further subdivide anaerobic metabolism into the phosphagen (alactic) pathway and the glycolytic (lactic-acid) pathway. Aerobic metabolism can occur both in oxygen-dependent or oxygen-independent modes; the latter tends to overlap with glycolytic metabolism.

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Fat Loss and Running

For some reason people seem to have the idea that running will create fat loss. There’s two ideas that probably contribute to this: the best runners are usually very lean, and the 1980s obsession with aerobics. The latter especially created a tradition so that “everybody knows” you go run or do aerobics classes to get in shape. Right?

As usual, it’s not that easy. There is some truth to the fact that steady-state aerobic exercise does tend to preferentially use circulating triglycerides as a fuel source (body fat, effectively). However as the current fad towards interval training will quickly remind us, the fuel source isn’t the entire story. There’s something to be said for shorter, more intense exercise. I won’t go into the details because they aren’t terribly important here, but maximal activation of anaerobic metabolism tends to chew up more calories and do favorable things for nutrient partitioning: calories go to muscle instead of fat storage, and more fat ends up being burned over a 24-hour period.

Keep on reading &rarrow;Fat Loss and Running