by Gabe Mirkin, M.D.
Calorie counts listed on food packages or restaurant menus are deceptive because they tell how much energy that food has when it is burned in a laboratory. The number of calories absorbed in your body is likely to be quite different, depending on how the food is prepared and what types of bacteria you have in your colon.
Food that is absorbed from your intestines and colon is either burned for energy and body functions, or stored as fat in your body. The less food that is absorbed, and the more that is burned by being active, the easier it will be to maintain your ideal weight. 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 starchy vegetables increases the number of calories you absorb from those foods.
How You Absorb Food
You 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.
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. Much of the foods that you eat passes to your colon where more than 100 trillion bacteria do have the enzymes to break down food so you can absorb a lot of calories through your colon.
Some types of bacteria in your colon may make you fatter, while others could help you to stay slim. One study on mice done by Jeffrey Gordon at Washington University in St. Louis showed that feeding mice a diet high in fat and low in fruits, vegetables, and other sources of soluble fiber reduced amounts of healthful Bacteroides and increased amounts of fattening Firmicutes in their colons to significantly increase absorption of calories from their food (Science, Sep 6, 2013:341(6150)). He then placed skinny mice in the same cages as the fat mice fed this unhealthful diet and they also became fat, presumably because mice acquired each other’s bacteria by eating their stool.
Raw Starches are Poorly Absorbed
When humans eat raw root vegetables such as potatoes, turnips, cassava, yams, and rutabagas, they absorb almost no calories. However, boiling, baking or frying them markedly increases the calories you can absorb. Starches in root vegetables or in whole grains such as wheat are composed mostly of multi-sugar molecules called amylopectin and amylose, which your digestive enzymes have great difficulty breaking down. Cooking gelatinizes starches so they are easily exposed to intestinal enzymes that break them down so they are readily absorbed, and the remainder passes to your colon where bacteria break them down further so you absorb even more calories.
Whole grains such as wheat, rye, barley, rice and quinoa are seeds of grasses. Uncooked, they cannot be broken down at all and will pass out undigested. Even when whole grains are cooked, the enzymes in your intestines often cannot break through the tough outer seed coating, so they are hard to absorb. However, if you grind a whole grain into flour, it is easily absorbed, and cooking the flour (in pasta, bakery products and so forth) increases the calories you absorb even more.
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. Cooking 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.
Many body builders and weight lifters eat raw eggs with the belief that raw eggs grow larger muscles, but 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 single amino acids and chains of amino acids, but not whole proteins, can pass readily into your bloodstream.
Soft Foods Have More Calories
Rats who ate uncooked cereals that were softened by being puffed with air (similar to “puffed wheat” or “puffed rice” cereals) were six percent heavier and had 30 percent more abdominal fat than rats who had been fed hard cereal pellets for 22 weeks (Journal of Dental Research, 2003;82:491-494). Abdominal fat is a sign of higher blood sugar and insulin levels and risk for diabetes. 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.
If you are trying to lose weight or to control your weight, forget about counting calories. Eat more foods that are not cooked, ground or softened.
• Eat a wide variety of raw vegetables and fruits.
• 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.
• Avoid 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.
I also recommend Intermittent Fasting for weight loss and long-term weight control.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe's full bio.