A study conducted by the Institute for Nutrition and Cancer Research (INCR) discovered that 78% of adults agreed with the statement “the kind of foods you eat is more important than the quantity of food you eat” in regards to weight management. This raises many points of contention. Very good arguments can certainly be made for and against the statement. Indeed, it is true that your overall caloric balance during a given day will determine whether or not your weight changes. On the other hand, food choices can influence that caloric balance by influencing metabolic rate, the thermic effect of food (TEF), and satiety. In order for one to lose weight, and hence, body fat, one’s caloric expenditure must exceed their caloric intake and this requires energy intake control, and thus the quantity of food must be controlled1.
It is pertinent to state that one should eat healthy foods when on a weight loss diet. Fruits, vegetables, low fat meats, and the like are good sources of vitamins, minerals, and fiber (in the case of fruits and vegetables) and these can certainly impact one’s health. However, one can not simply eat as many “good” foods as they like with reckless abandon and expect not to gain weight. It is certainly easier to achieve a caloric surplus eating twinkies all day than it is to achieve that same surplus though fruits, vegetables, and lean meats, however if the person eating only twinkies makes a conscious effort to limit their twinkie intake to a caloric level that is less than the amount of calories they expend per day, they will lose weight whereas a person who eats an unlimited amount of “good” foods will still gain weight if they consume more calories than they expend. Obviously, eating only twinkies or foods similar to it is not a good strategy for weight management, but it is an extreme example used to support my points.
Those who agree with aforementioned statement will most likely try to argue that the specific foods you eat are more important than the quantity that you eat will use the argument that “a calorie is not a calories” to support their stance. In other words, they believe that certain foods may provide a metabolic advantage over other foods. There certainly is ample evidence to support this stance. For example, diets higher in protein are less “energy efficient” as the conversion of alanine to glucose during gluconeogenesis requires six ATP molecules per mole2 and the conversion of pyruvate to glucose also consumes six ATP molecules per mole.3 Furthermore, four molecules of ATP are required to dispose of the nitrogen as urea.3 Maintaining the turnover of body proteins (i.e. folding, targeting, synthesis, and breakdown) is also energetically very costly.4 In fact, the thermic effects of nutrients are approximately 2-3% for lipids, 6-8% for carbohydrates, and 25-30% for protein!5 This increased thermic effect of food (TEF) seems to cause increased weight loss in high protein diets compared to diets equal in calories but higher in carbohydrates.6 The fiber content of a diet is also another issue to consider. Dietary fiber contains far less metabolizable energy than starchy carbohydrates due to incomplete absorption of fiber. In fact, using the Atwater values (4 kcal/g CHO, 4 kcal/g PRO, & 9 kcal/g FAT) to calculate metabolizable caloric intake may overestimate intake by as much as 3-7% when the fiber content of the diet is increased.7
It is therefore tempting to state that one could eat a high protein/low carbohydrate/increased fiber diet and not need to concern themselves so much with portion size because there is a far smaller net energy gain when consuming such a diet as compared to a typical higher carbohydrate diet. Although the net energy gain is much smaller on a high protein/low carbohydrate/increased fiber diet, the fact remains that it is still quite possible one can consume more calories than they expend if they fail to control the quantity of food that they take in. Controlling food intake and self monitoring is crucial in any weight loss or weight maintenance regime. In fact, Hill et. al, found that the majority of people who successfully lost weight (at least 13.6 kg) and maintained that weight loss for at least one year practiced some form of cognitive restraint, including restricting certain foods, portion sizes, counting calories, etc.8 So while it may require a greater quantity of food on a high protein/low carbohydrate diet to exceed one’s caloric expenditure, it can still be done, and therefore the quantity of food must be controlled.
While controlling the quantity of food one eats may be more important than the types of foods one eats in regards to weight maintenance/loss, it is important to note that the types of foods that one eats will impact the quantity of foods that one will consume as well. Diets high in protein and high fiber have both shown to reduce hunger compared to a higher carbohydrate or reduced fiber diet.8,9 Additionally, the research seems to support the hypothesis diets higher in dietary protein have an increased thermic effect of food, allowing for greater weight loss at ‘equal’ calorie intakes when compared to higher carbohydrate diets. Therefore, the most successful strategy in achieve fat loss/maintenance may be to practice cognitive restraint while eating a high protein/reduced carbohydrate/high fiber diet.
1) Wardlaw GM, Kessel M. Energy Production and Energy Balance. In: Perspective in Nutrition 2nd Ed. New York,NY: McGraw-Hill Higher Education; 2002. p. 535-537.
2) Feinman RDand Fine EJ. A calorie is a calorie violates the second law of thermodynamics. Nutrition J. 2004, 3:9.
3) HueL. Regulation of gluconeogenesis in liver: In: Jefferson L, Cherington A, eds. Handbook of physiology: the endocrine system. Vol 2. Oxford,United Kingdom: OxfordUniversityPress, 2001:649-57.
4) Bier DM. The energy cost of protein metabolism: lean and mean on Uncle Sam’s team. In: The role of protein and amino acids in sustaining and enhancing performance. Washington,DC: National Academies Press, 1999:109-19.
5) Jequier E: Pathways to obesity. Int J Obes Relat Metab Disord 2002, 26 Suppl 2:S12-7.
6) Westman EC, Mavropoulos J, Yancy WS, Vlek JS: A review of low-carbohydrate ketogenic diets. Curr Atheroscler Rep 2003, 5:476-483.
7) Buchnolz AC and Schoeller DA. Is a calorie a calorie? Am J Clin Nutr, 2004:79(suppl): 899S-906S.
8) Nickols-Richardson SM, Coleman MD, Volpe JJ, Hosig KW. Perceived hunger is lower and weight loss is greater in overweight pre-menopausal women consuming a low-carbohydrate/high-protein vs. high-carbohydrate/low-fat diet. J. Am. Diet. Assoc. 2005 Sep;105(9):1433-7.
9) Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation.
Nutr. Rev. 2001 May;59(5):129-39.
By: Layne Norton
“Layne Norton Unleashed” on DVD for sale at: www.biolayne.com