The article, “Carbohydrate Restriction and Constipation”, explains why increasing those dietary saturated fats, of which the melting points are higher than the human body temperature, would increase the risk of constipation. [1] This relationship helps ponder the myths regarding (1) the existence of a perfect gastrointestinal system; (2) the rationale of counting dietary calories for weight control; (3) the reason that why carbohydrate-restricted diet helps lose weight.
In the above-referenced article, observation has shown that, other than consuming more green leafy vegetable or fibers along with plenty of water, replacing the high-melting-point animal saturated fats, which are usually the long-chain triglycerides, with the medium-chain triglycerides and/or unsaturated fats will reduce the possibility of constipation. Such observation at least implicates that some of the dietary fats are not digested or absorbed by the small intestine, and are sent into the large intestine and destined for waste. This means there is no perfect gastrointestinal system, which can digest and absorb all foods, which the mouth takes in.
Among macronutrients, providing no genetic disorder concerning the lack of certain enzyme or enzymes, carbohydrates except the indigestible fibers are readily digested with the help of amylase in the saliva and pancreatic secretion, and completely absorbed by the small intestine, before they reach the cecum, which is the beginning of the large intestine. Re-routing the small intestine in bariatric surgery is to let carbohydrates by-pass the small intestine and to reduce their digestion and absorption. Bariatric surgery achieves carbohydrate restriction for weight loss with scalpel. [2, 3]
Since there is no perfect gastrointestinal system for digesting and absorbing all foods, which the mouth takes in, blaming the excess calorie intake alone for gaining weight does not make sense. The calories in excess from consuming carbohydrates, except indigestible fibers, are responsible for obesity. However, the calories in excess from consuming more calories from fats and proteins are likely not. [4]
In converting proteins into glucose for supplying energy to the body, each gram of proteins loses one calorie to heat and nets only three calories. [5] Thus, diet, which is high proteins, helps lose weight.
Animal studies have shown types and amount of fats affect the pancreatic lipase activity. [6] Insulin-dependent diabetic suffers from low lipase activity. [7] Although the exact mechanism has not been understood yet, low insulin level apparently decreases pancreatic lipase level. Perhaps, dieters with carbohydrate restriction, which maintains a lower level of functioning insulin, may have a lower level of lipase and cannot digest and absorb all the fats of the diet, even if these dieters consume more in calorie from fats.
In summarizing the above findings, carbohydrate restriction helps lose weight because of a number of reasons. (1) As long as carbohydrate is restricted, blood glycemic level is expected less fluctuating and within normal range, which requires little insulin secretion. (2) Little insulin secretion likely results in less lipase activity, which may be responsible for inability of completely digesting and absorbing the fats of the diet, thus, prevents or slows excess calorie intake. (3) Little insulin secretion helps avoid hypoglycemia, which is responsible for frequent eating carbohydrates and excess calorie intake. (4) Diet high in fat and protein helps provide a lasting satiation, which means reducing the appetite for excess calorie intake and facilitating weight loss without starvation or scalpel.
Robert Su, Pharm.B., M.D.
References:
- Su RK “Carbohydrate Restriction and Constipation.” The Blog. Carbohydrates Can Kill. December 26, 2011.
- Su RK “Bariatric Surgery: Credits Go To Restricting Carbohydrate Absorption (1 of 2)”, The Blog, Carbohydrates Can Kill. January 20, 2010.
- Su RK “Bariatric Surgery: Credits Go To Restricting Carbohydrate Absorption (2 of 2)”, The Blog, Carbohydrates Can Kill. January 27, 2010.
- Su RK “An Overview of Dieting for Health: The Diet.” The Blog, Carbohydrates Can Kill. August 4, 2010.
- Feinman RD. “’A calorie is a calorie’ violates the second law of thermodynamics.” Nutritional Journal. Volume 3, Number 9. July 28, 2004.
- Ricketts J & Brannon PM “Amount and Type of Dietary Fat Regulate Pancreatic Gene Expression in Rats.” Journal of Nutrition. 1994 Aug;124(8):1166-71.
- Junglee D et al “ Low pancreatic lipase in insulin-dependent diabetics.” J Clin Pathol 1983;36:200-202
