|Fat Burning Update
Colin Carriker and Len Kravitz, Ph.D.
Whether an exercise enthusiast, elite athlete, or an occasional gym visitor, the concept of fat loss can become an obsession for many people. On a daily basis personal trainers are consistently asked questions such as 'what exercises burn the most calories' or 'which nutrition supplements enhance fat burning'. From a health perspective it is important to emphasize that the more abdominal fat (i.e, visceral or central fat) a person has, the higher the association with developing insulin resistance, type 2 diabetes, heart disease, some cancers (endometrial, breast, and colon), and some disabling degenerative diseases of the joints (WHO, 2011). This column will answer 10 contemporary questions on fat burning and fat burning supplements.
1) Will I prevent weight gain by predominantly consuming a diet of carbohydrates and proteins? Fat contains 9 calories/gram, carbohydrate contain 4 calories/gram, protein contains 4 calories/gram and alcohol contains 7 calories/gram. Ultimately, the over consumption of total calories coupled with reduced caloric expenditure (via reduced physical activity) will result in a caloric imbalance. This type of caloric imbalance will result in a net caloric gain in weight, often as increased body fat. If fat is reduced meaningfully from the diet there are still other substrate avenues for extra calories to enter the body. Bray et al. (2012) investigated the over consumption of calories with diets of low, normal, and high amounts of protein. Interestingly, the increases in body fat were similar in all three protein diet groups. The authors concluded that the increased calorie consumption alone was responsible for the similar increases in fat content.
2) Does L-Carnitine supplementation increases muscle mass, improves fat metabolism, and enhances fat loss as made by the advertising claims? L-carnitine is found in large quantities in meat and has been a supplement of interest for two decades. The primarly function of L-carnitine is to transport long-chain fatty acids across the inner membrane of a muscle cell's mitochondrion (ATP synthesis organelle), where they are further dissembled. There is a belief that regular L-carnitine supplementation will help with weight loss by increasing the cell's concentration of carnitine, and thus increasing the fatty acid transport for enhanced fat metabolism. Unfortunately there is no solid scientific evidence supporting this claim (Jeukendrup & Fandell, R., 2011).
3) Is the consumption of liquid calories a viable weight loss plan?
While it may seem logical that the consumption of liquid calories won't accumulate body fat, this couldn't be further from the truth. What should be recognized is the energy balance (calories in vs. calories out) over a day or week. Many beverages are sweetened with sugar and have very little nutritional benefit. Research indicates the high consumption of beverages which have these added calories, particularly sweetened drinks with high-fructose corn syrup, may be a contributing factor to the obesity epidemic confronted today (Bray, Nielsen & Popkin, 2004).
4) Will the intake of caffeine improve energy expenditure at rest and during exercise?
Caffeine has been shown to increase sympathetic nervous system activity, thus releasing fatty acids from adipose and intramuscular tissues storage depots. Caffeine has also been associated with metabolic processes that enhance fat breakdown (Jeukendrup & Fandell, 2011). Although the effects of caffeine do seem to acutely enhance metabolism at rest and during lower low-intensity exercise (less at moderate- to high-intensity exercise), Jeukendrup and Fandell conclude that the effects are small.
5) Should all fat intake be reduced in the diet?
Some fats should be consumed minimally, including both saturated and trans fatty acids. However, research indicates the addition of omega-3 fatty acids into the diet may be linked to a reduced incidence of cardiovascular disease. Omega-3 fatty acids are also linked to the management of hypertension (depending on the degree of an individual's hypertension). Omega-3 fatty acids may also aid in lowering triglycerides as well as reduce the risk of mortality due to cardiac arrhythmias (Kris-Etherton, Harris & Appel, 2002).
6) Does fucoxanthin supplementation lead to weight loss?
Fucoxanthin is a carotenoid found in edible brown seaweeds. Some weight-loss companies are promoting it as a weight loss supplement. The one study on this product showed positive results, yet caution is suggested as one of the authors works for the company that holds patents for fucoxanthin (Jeukendrup & Fandell, 2011). Also, seaweed has several times the amount of iodine that most adults require on a daily basis. Therefore, a possible side effect could include changes in thyroid function due to iodine surplus.
7) Is it worth it to take conjugated linoleic acid for fat loss?
Conjugated linoleic acid (CLA) is promoted as an anti-obesity agent. Claims suggest that it increases energy expenditure, fat oxidation, lipolysis (the disassembly of fats), and dampens appetite. More recent research shows that supplementation of 3 grams per day CLA will result in some fat loss (1 lb per week) (Jeukendrup & Fandell, 2011).
8) What are the best exercises for weight loss?
First and foremost, determine exercises that clients enjoy consistently doing. A combination of resistance exercise and cardiovascular training is key to weight loss success. Resistance training helps to preserve muscle mass during calorie restriction eating. It also modestly increases energy expenditure after each training session for a couple or hours. For increased energy expenditure from exercise, a combination of weight bearing and non-weight bearing cardiovascular exercises is recommended (i.e., jogging, cycling, elliptical training, rowing, stair stepping, etc.) to avoid overuse injuries. Mix up cardiovascular workouts to include long low-intensity continuous training bouts, short fast continuous exercise training sessions and high intensity interval training.
9) Will taurine promote weight loss?
Taurine is an amino acid that is necessary for normal skeletal muscle functioning and is popularly promoted for weight loss. One study has shown a favorable increase of fat oxidation during exercise with taurine ingestion (Jeukendrup & Fandell, 2011). Further investigations are necessary to best determine the efficacy of taurine for weight management programs.
10) Is forskolin a weight loss supplement of the future?
Forskolin is produced by the roots of a family of Coleus plants that are cultivated in India, Thailand and parts of southest Asia. It is currently hypothesized that forskolin may increase the activation of the enzyme hormone-sensitive lipase, an enzyme the increases the breakdown of fat and thus better fat oxidation. Although there is only one published study with forskolin, the positive results suggest more study is warranted to determine optimal dosages for this supplement's use for fat metabolism.
Side Bar 1. Can a Person be Fit and Fat?
Those individuals who tend to carry a larger proportion of fat mass have an increased risk of cardiovascular disease, pre-diabetes, type 2 diabetes and high blood pressure. However, body fat or BMI should not be viewed independently. Exercise professionals recognize the many benefits of cardiorespiratory fitness. Although lesser known, individuals who are obese but active or fit may actually have a lower risk for mortality when compared to those individuals who are classified as normal-weight but are sedentary or unfit (LaMonte & Blair, 2006). As a general rule, those individuals who are obese and physically inactive or unfit exhibited the highest risk of mortality. Further, if individuals with a similar BMI are compared to each other, those with a greater cardiorespiratory fitness tend to have a lower risk for mortality especially when compared to individuals who are not physically active. Therefore, even improving cardiorespiratory fitness may reduce the risk of mortality independent of a reduction in BMI.
Arciero, P.J., Goran, M.I., & Poehl, E.T. (1993). Resting metabolic rate is lower in women than in men. Journal of Applied Physiology, 75(6), 2514-2520.
Bray, G.A., Smith, S.R., de Jonge, L., Xie, H., Rood, J., Martin, C.K., et al. (2012). Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating. The Journal of the American Medical Association, 307(1), 47 -55.
Bray, G.A., Nielsen S.J., & Popkin, B.M. (2004). Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. American Journal of Clinical Nutrition 79(4), 537-543.
Jeukendrup, A. E. & Fandell, R. (2011). Fat burners: Nutrition supplements that increase fat metabolism. Obesity Reviews, 12, 841-851.
Kris-Etherton, P.M., Harris, W.S., Appel, L.J. (2002). Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation, 106, 2747-2757.
LaMonte, M.J. & Flair, S.N. (2006). Physical activity, cardiorespiratory fitness, and adiposity: contributions to disease risk. Current Opinion in Clinical Nutrition & Metabolic Care, 9(5), 540-546.
WHO (2011). Overweight and Obesity.
Accessed January 24, 2012