More About Calories, Energy, and Protein

by: Dr. Gabe Mirkin, M.D.

Calories from Foods Vary with Preparation Method

Your body either burns the food you eat for energy or stores it in your body as fat. The less food you absorb, and the more you burn by being active, the thinner you will be. Anything that reduces the size of food particles or breaks down the chemical components of food increases the calories you absorb from that food. For example, grinding whole grains into flour or cooking vegetables increases the number of calories you absorb.

How Your Body Converts Food to Energy

Your body cannot absorb whole foods. Food is separated in your intestines into carbohydrates, fats and proteins. Your body cannot absorb these components either. Carbohydrates must be broken down into single sugars. Protein must be broken down into single amino acids or chains of amino acids, and fat must be broken down into fatty acids.

Image from Wikipedia.org

Absorption of Carbohydrates

Most foods that come from plants are made up primarily of carbohydrates: sugars that are single or in molecules of two or three up to millions of sugars bound together. Starches contain hundreds and thousands of sugars bound together. Fiber contains up to millions of sugars bound together so tightly that the human intestines cannot separate them and therefore cannot absorb them.

Humans can absorb only single sugars from the intestinal tract. For example, the sugar in milk is lactose: two sugars bound together. Most humans have an enzyme in their intestinal tracts called lactase that splits lactose into its two single sugars that are easily absorbed. However, some people have such low amounts of lactase that they cannot split the double sugar into single sugars. Therefore, these people cannot absorb the double sugar from their intestines, so it travels to the colon where bacteria ferment it to cause gas, belly cramps and diarrhea.

Raw Starches are Poorly Absorbed

Raw root vegetables such as potatoes, turnips, cassava, yams, and rutabagas are very low in calories. However, boiling, baking or frying them markedly increases their calories, and the longer you cook them, the more calories they provide. Root vegetables are low in fiber and high in starches. Cooking turns these poorly absorbed starches into sugars that are readily absorbed in your intestines.

Starches in root vegetables such as potatoes or in whole grains such as wheat are composed mostly of two-sugar molecules called amylopectin and amylose. Your digestive enzymes have great difficulty breaking them down. Cooking gelatinizes starches so they are easily exposed to intestinal enzymes that break them down so they are readily absorbed.

Flour Makes You Fatter

Whole grains such as wheat, rye, amaranth and quinoa are seeds of grasses. These seeds have tight capsules that cannot be broken down by the enzymes in your intestines so you cannot absorb them. However, if you grind a whole grain into flour, it is easily absorbed. Cooking the flour increases the calories you absorb even more.

Soft Foods Have More Calories

After 22 weeks, rats who ate uncooked cereals that were softened by being puffed with air were six percent heavier and had 30 percent more abdominal fat than rats who had been fed hard cereal pellets. This is a sign of higher blood sugar and insulin levels and risk for diabetes (Journal of Dental Research.2003;82:491-494). Researchers showed that the rats fed hard food had a higher rise in body temperature after meals because they used significant energy in the act of chewing and digesting the food. The hard-pellet rats also had nearly twice the volume of feces, showing that they had absorbed far less of their food.

Absorption of Protein

When you eat meat, you eat mostly muscle which is made of very poorly absorbed collagen. If you ate raw, un-ground meat you would get very few calories from it. Cooking meat causes the muscle fibers to loosen and separate, making it easier to chew and digest. It also changes the structure of the proteins, causing them to unwind and become more susceptible to intestinal enzymes that break down protein to increase absorption.

Grinding meat into hamburger markedly increases absorption and reduces the amount of time you have to chew it. Organ meats such as kidneys, liver and brains are also easier to digest because they are low in collagen so you do not have to chew them as long as when you eat muscle.

Body Builders and Raw Eggs

Many body builders and weight lifters eat raw eggs with the mistaken belief that raw eggs grow larger muscles. When you eat uncooked eggs, you absorb less than 50 percent of their protein. When you eat cooked eggs, you absorb up to 95 percent. Heat denatures protein so that the protein molecules swell and are more exposed to the intestinal enzymes that separate protein into its building blocks called amino acids. You then absorb a much greater percentage of the protein because amino acids, not whole protein, pass into your bloodstream.

How to Use this Message for Weight Control

If you are trying to lose weight, eat more foods that are not cooked, chopped, ground or softened in any way.

• Eat lots of raw fruits and vegetables.
• You can eat cooked fruits and non-starchy vegetables also, because they are usually low in calories even when cooked.
• Eat WHOLE grains, beans, seeds and nuts that have not been ground into flour.
• Restrict sugared drinks because virtually 100 percent of their calories are rapidly absorbed.
• Restrict all sugar-added foods.
• Restrict foods made from flour such as bakery products and pastas.