Saturday, October 2, 2010

A Calorie Is Not a Calorie!



My sister is always reading the caloric information on the side of boxes. I always knew that it was more important to eat clean, healthy, natural foods than to concern yourself with how many calories you’re eating. If you’re eating tons of veggies, fruits, organic meat, nuts, and fish, you do not have to worry about your weight. Eating this way will keep your full and your appetite in control. Having said all that, people still are concerned about “calories” so I will talk about it. Mostly because nutritionists and dietitians use it as a unit of measurement to help people lose weight.

Calorie counting is not as simple as it sounds. The law of thermodynamics state that as long as your calories in = calories out, you will stay the same weight. If your caloric intake is greater than your caloric expenditure, you will gain weight and vice versa. Advocates of the low fat diet use this law to explain their reasoning. A gram of fat contains 9 calories, carbohydrates and protein, on the other hand, contain 4 calories per gram. Therefore, eating less fat means fewer calories, which means you’ll lose weight, right? Wrong. Low fat often means high carb, and ever since the government instituted the Canada Food Guide some 30 years ago, we have only seen obesity, diabetes, and osteoporosis rates rise exponentially. It’s not as simple as it sounds. Here’s why.

1. Thermic Effect of Food

People treat calories in and calories out as independent factors but they are not. They are actually dependent factors as they affect one another. The energy cost to metabolize protein, fat, and carbohydrates is different. It takes more energy to digest protein than it does to digest carbohydrates and fat. For example, a 2000 calorie diet containing say 30% protein will make you expend more energy than a 2000 calorie diet containing 20% protein. Remember the energy balance teeter totter above? Eating different foods (left side) will affect the calories out (right side). People often only think the right side as exercise and daily lifestyle activities. Now you know that different foods will affect your total caloric metabolism at the end of the day.

2. Caloric restriction slows down metabolism

If you decide to cut calories in order to lose weight, you will probably start seeing an immediate weight loss in the beginning. However, the rate of your weight loss will slow down in subsequent weeks. That’s because as you start restricting your calories, your body runs cooler to conserve the reduced calories you’re taking in.

3. Different foods have different effects on your appetite

This has everything to do with hormones. When you eat a high carbohydrate meal, it breaks down into sugar in your blood. This causes a spike in insulin to communicate with the cells in your body to store the sugar. The spike in insulin is followed by a sharp fall in blood sugar which will then make you feel hungry again. Eating fat and protein affects satiety hormones like PPY and leptin, making you feel fuller longer.

4. Timing of meals affect calorie processing

Food calories are more likely to be stored as fat if not used immediately for energy. When liver and muscle glycogen stores are full, carbohydrates get converted and stored in the fat cells. On the contrary, food calories are more likely to be used for energy, stored as glycogen, and protein synthesis at times of an energy deficit such as first thing in the morning and right after exercise. That’s why pre and post workout nutrition is extra important. The best time to consume high glycemic carbohydrates is after your workout when the insulin spike is crucial for replenishing glycogen stores.

In conclusion, counting calories has some value but should be used with a grain of salt. As cited in the reasons above, there is a lot more to gain from eating good quality foods than there is from counting calories.

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