Food and Metabolism

There have been studies up studies on how eating various foods can affect how fast we burn up calories. Basically, can eating certain types of calories help you burn calories faster? I’m sure you’ve heard of “negative calorie foods.” If you google that, you will find lists and charts and articles describing this magic list of fruits and veggies. Sounds like hokum to me, but I figured I would do some investigating.

negative

When we consume food, energy (calories) is used to break down and digest the food and store it, absorb its nutrients, and send what’s left off for other purposes. This small allotment of energy we use to do this is called the “thermic effect of food” or TEF. We all burn a certain amount of calories while we are at rest just to keep up bodily processes and functions. This is called the resting metabolic rate and is subtracted from total energy burned to come up with TEF (1, 2). The TEF magnitude depends on the food content and quantity (3, 4).

Carbs: 5-15% of intake is burned by TEF

Fats: 5-15%

Proteins: 20-35%

Get that protein.

For example, the most commonly claimed negative calorie food is celery. Celery only has an 8% TEF. A single stalk contains about 6 calories and only half a calorie is burned in the digestion process (5). The only truly negative calorie food is ice water which contained no calories and burns only a small amount to regulate the temperature (6). Other foods touted for their negative calorie nature include grapefruit, lemon, apple, lettuce, lime, broccoli, and cabbage. People who make these foods staples tend to lose weight, but not because these foods are negative calorie. It’s because they are low calorie and healthy whole foods (5).

Calories may not be created equal, however. The calories in , calories out mantra that has been preached may be wrong in one respect. Whole food sources create a larger TEF. In a 2010 study, 17 healthy male subjects were given either a processed lunch of white bread and cheese product, or whole grain sprouted bread and sharp cheddar. Both lunches had the same calorie count, and the subjects were monitored for the 6 hours following lunch consumption. For the processed food group, TEF was measured to be 10% of the energy per calories consumed, while the non-processed group burned 20% (7) I don’t approve of any of the food given to the study subjects, but it’s not my study.

Since we have discussed all of the physiological changes in our bodies that exercise brings, let’s go over how exercise can help to increase TEF. There are two components that contribute to the energy consumed in TEF. One is the obligatory component that we have already discussed. Food energy is used up by digestion and nutrient absorption. The other component is the faculative component which is determined by sensitivity to glucose (8) and activity of the sympathetic nervous system (9). The energy intake induces the sympathetic nervous system. This system up-regulates what is called the beta- adrenergic receptor (BAR). This receptor is responsible for stimulation of cellular energy metabolism, therefore, larger TEF (10, 11). In a 2007 study comparing frequent exercisers to more sedentary individuals, TEF and responsiveness of the BAR were measured. Four hours after energy intake, responsiveness and TEF were measured with the following results. (Isoproterenol activates BAR. Responsiveness was dependent on treatment.)

Increase (Δ) in energy expenditure above resting energy expenditure during β-adrenergic receptor (β-AR) stimulation (intravenous isoproterenol) was greater in habitual exercisers than in sedentary adults. Values are means ± SE. FFM, fat-free mass. *Main effect of activity status (P = 0.01) and interaction (dose × activity status) (P = 0.25).

Increase (Δ) in energy expenditure above resting energy expenditure during β-adrenergic receptor (β-AR) stimulation (intravenous isoproterenol) was greater in habitual exercisers than in sedentary adults. Values are means ± SE. FFM, fat-free mass. *Main effect of activity status (P = 0.01) and interaction (dose × activity status) (P = 0.25).

 This study has shown that increased TEF in habitual exercisers causes a higher responsiveness of BAR to the nervous system leading to a higher rate of cellular energy burn (12).

Exercise and eat right and your body will reward you.

rewrd

1. Denzer, CM; JC Young (2003 September). “The effect of resistance exercise on the thermic effect of food.”International Journal of Sport Nutrition and Exercise Metabolism 13 (3): 396–402.

2. Edward F. Goljan (2013). Rapid Review Pathology. Elsevier Health Sciences. p. 174

3.  Christensen, Peter. “What is the thermic effect of food?”. Retrieved March 28, 2005.

4. http://www.jacn.org/content/23/5/373.long

5. Marion Nestle; Malden Nesheim (18 April 2012). Why Calories Count: From Science to Politics. University of California Press. pp. 189–190.

6. De Nileon, Gay Porter (2009). Plain Talk About Drinking Water: Answers to Your Questions About the Water You Drink. American Water Works Association. p. 4.

7.  Camastra, S.; Bonora, E.; Del Prato, S.; Rett, K.; Weck, M.; Ferrannini, E. (1999). “Effect of obesity and insulin resistance on resting and glucose-induced thermogenesis in man. EGIR (European Group for the Study of Insulin Resistance)”. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity 23 (12): 1307–1313.

8. Laville M, Cornu C, Normand S, Mithieux G, Beylot M, Riou JP.Decreased glucose-induced thermogenesis at the onset of obesity. Am J Clin Nutr 57: 851–856, 1993.

9. Deriaz O, Nacht CA, Chiolero R, Jequier E, Acheson KJ. The parasympathetic nervous system and the thermic effect of glucose/insulin infusions in humans. Metabolism 38: 1082–1088, 1989.

10. Acheson K, Jequier E, Wahren J. Influence of β-adrenergic blockade on glucose-induced thermogenesis in man. J Clin Invest 72: 981–986,1983.

11. Acheson KJ, Ravussin E, Wahren J, Jequier E. Thermic effect of glucose in man. Obligatory and facultative thermogenesis. J Clin Invest 74:1572–1580, 1984.

12. Stob NRBell Cvan Baak MASeals DR.  Thermic effect of food and beta-adrenergic thermogenic responsiveness in habitually exercising and sedentary healthy adult humans. J Appl Physiol (1985). 2007 Aug;103(2):616-22

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