Sometimes eating fewer calories can make you fatter
Sooner or later, you're going to have to face up to the fact that your body and your bank account just don't work in the same way. When you deposit 1000 quid at your local financial institution, your savings account will be richer by exactly that amount, but slipping 1000 calories down your gullet can have a variety of effects on your personal reserves of body fat, depending on the exact composition of those calories.
That's the news from Indiana University, where recent research has shown that sometimes you can step up your caloric intake with little risk of getting fat - or reduce your total food consumption and attach a wide belt of blubber to your hips!
To unearth this surprising information, Indiana researchers simply put two groups of athletic laboratory rats on different diets. One collection of rodents consumed a high-fat diet, with 79 per cent of the calories coming from pure lard, while a second assemblage of rodents followed a high-carbohydrate regime, with 68 per cent of calories supplied by carbohydrate. However, the high-fat rats actually consumed 11-per cent FEWER calories per day over the five-week period.
All rats trained in an identical fashion, working out for 90 minutes per day, five days per week, by running on an inclined treadmill at a tempo of 29 metres per minute (that's a sizzling - by rat standards - 55 minute per mile pace). Thus, total calorie burning was similar in the two groups.
After five weeks, the rats who ate fewer calories were slimmer, right? Guess again. In fact, the two groups were exactly equal in weight, and per cent body fat for the low-calorie rats was 17 per cent, versus a svelte 14 per cent for the higher-calorie, carbohydrate-consuming rodents.
Why did eating fewer calories translate into greater body fatness? The answer, according to the Hoosier researchers, is that rats, like humans, are very efficient at storing dietary fat but a bit inept at converting carbohydrate to fat and then socking it away as surplus adipose tissue. By some estimates, as much as 97 per cent of ingested fat can be stored as body fat, while no more than 70 per cent of dietary carbohydrate can be tucked away.
But that's only part of the story. Much of the fat from your dinner plate is laid aside as body fat; the rest is used by your body as a source of energy. The dietary fat that's metabolized tends to take the place of body fat which might otherwise have been burned. The overall result is that there's little opportunity for your already-existing supplies of body fat to be whittled away.
The carbohydrate in your bowl behaves a bit differently. True, some of it can be stored as fat, but much is deposited as surplus carbohydrate (glycogen) in your muscles and liver. The rest of the incoming carbohydrate can be blended with the fat which has slipped into your bloodstream from your fat cells, and this carbo-fat mixture can be metabolized by various organs in your body. The bottom line is that a 1000-calorie serving of carbohydrate can usually nudge your body fatness up only a little, while a 1 000-calorie dose of fat can spread rich layers of butter under your skin.
True, eating more fat does 'teach' your muscle cells to burn a little more fat over the course of a day, but as fat is such a light tissue your bathroom scales scarcely notice this process. Also, since fat is stored so easily, the fat gobbled up by your muscles can readily be replaced on your buttocks and thighs by the fat carried into your mouth by your fork.
Overall, increasing your per cent body fat becomes easier as you ingest more high-fat foods, even if your overall intake of calories is quite modest. On the other hand, getting portly is hard when carbohydrate consumption is the order of the day. Don't be fooled, though. Many 'high-carbohydrate' foods, notably biscuits, cakes, pies, and candy bars, are laden with rich lodes of fat. Stepping up your intake of these is a sure way to pad your body with bloated adipose cells. 'Dietary Fat Promotes Body Fat Storage during Exercise Training When Energy Intake is Reduced,' Medicine and Science in Sports and Exercise, vol. 26(5), Supplement, p. 559, 1994