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Exercise is medicine: weight training for belly fat?

Visceral adiposity is now recognized as a major risk factor in heart disease and a key clinical symptom of the metabolic syndrome. From the physician's perspective, the goal of treatment for obesity-related illnesses is to restore metabolic function. However, telling patients you can get rid of their belly fat can be a more powerful motivator than telling them you can lower their fasting blood glucose, normalize triglycerides, or decrease their hemoglobin A1 c. Weight training is beginning to show promise in all of these areas and may have particular benefit in addressing an expanding waistline.

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Mechanisms Around Belly Fat

Weight training has several unique mechanisms, aside from caloric considerations, that could aid the reduction of belly fat. It has both a positive impact on adrenergic receptors and unique hormonal effects. Beta-adrenergic receptors, when stimulated by catecholamines, turn on lipolysis through cAMP-mediated events. This same lipolytic response is blunted by alpha-adrenergic receptors. It has been shown that beta-adrenergic responsiveness is lowered in the abdominal adipose tissue of the obese. (2) Strength training can restore the balance and function of beta-and alpha-adrenergic receptors.

In the late 1980s, swimmers and distance runners were compared with weight lifters to evaluate the baseline catecholamine responses and adrenergic receptor types at rest. (5) At that time, it was shown that aerobic exercisers had greater alpha-adrenergic receptor density and significantly lower beta-adrenergic receptor density than weight trainers. The weight trainers showed the reverse of this trend, hinting at a greater capacity to burn fat.(5)

Weight training also has unique hormonal activity. Resistance exercise has been shown to raise levels of testosterone and human growth hormone (HGH) in a linear fashion with rising intensities, both of which have an important impact on reducing belly fat. (6), (7) HGH and testosterone oppose the action of glucocorticoids, as well as influence adrenergic receptor density (12), (13) HGH opposes the fat-storing action of cortisol at the belly, and testosterone leads to the production of a greater concentration of betareceptors in adipose tissue. The synergistic effect of these actions would enhance lipolytic activity of visceral adipose and make it more susceptible to fat loss both at rest and during future exercise sessions.

Studies on Resistance Exercise and Visceral Adipose

A study out of East Carolina University published in 2007 in the Journal of Applied Physiology showed weight training's ability to burn belly fat both during and long after a workout. (1) Subjects in this study had probes inserted in their adipose tissue. These probes stayed in place before, during, and 45 minutes after a resistance training workout. The session consisted of a full-body resistance-training workout using heavy weights lifted for 3 sets of 10 reps. At the end of the workout, researchers found that resistance training increased the usage of abdominal fat during exercise and for at least 40 minutes afterward. (1)

Another study published in 2007 by Schmitz et al. demonstrated the ability of resistance training to halt the accumulation of visceral adipose accumulation specifically in women. (11) One hundred sixty-four obese women were followed for two years, with one group engaging in 30 to 60 minutes of aerobic activity every day and the other group participating in a structured weight-training program twice per week. At the end of the 24 months, the aerobic group had a 21% increase in belly fat, while the weight-trained group group only saw a 7% increase. The researchers highlighted the fact that twice-per-week weight training was very well tolerated and had a major impact on age-related belly fat accumulation.

Finally, a 2009 review article by Tresierras et al. examined research on weight training spanning over 50 years. (10) The research showed that resistance training had special merit in helping to maintain insulin sensitivity. The researchers noted that sensitivity to insulin is directly related to muscle mass and inversely related to adipose tissue. (8-10) This is an important consideration, since the major outcome of resistance training is the addition or maintenance of lean body mass. While aerobic exercise can decrease adipose tissue, it does little to improve muscle mass, which is significantly lost during the aging process. The review also looked at adherence and safety profiles of weight lifting. Interestingly, resistance training was able to generate similar or superior results to that of aerobic exercise, though at lower intensity levels and decreased frequencies.

Prescribing Weight Lifting for Belly Fat

The studies highlighted here and in the review article by Tresierras et al. show a simple formula for prescribing resistance training. The whole body should be worked 2 to 3 times per week. The weights should be moderately heavy, with a repetition range of 8 to 12 per exercise, completed through 1 to 3 sets.

We use a simple formula for weight training prescription we call PPL (push, pull, legs). Pushing exercises refer to upper body movements in which the weight is pushed away from you (bench presses, shoulder presses, triceps press-downs, etc.). Pulling exercises are upper-body movements in which weight is pulled toward the body (back rows, barbell curls, pull-ups, etc.). Leg exercises are lower-body exercises (squats, leg presses). A good resistance-training program for belly fat reduction should include 2 to 3 exercises for each movement type. The weights should be heavy enough to induce failure at 8 to 12 repetitions.

by Jade Teta, ND,CSCS, and Keoni Teta, ND, LAc, CSCS jade@metaboliceffect.com keoni@metaboliceffect.com

Notes

(1.) Ormsbee et al. Fat metabolism and acute resistance exercise in trained men. J Appl physiol. 2007;102(5):1767-1772.

(2.) Polak et al. Dynamic strength training improves insulin sensitivity and functional balance between adrenergic alpha 2A and beta pathways in subcutaneous adipose tissue of obese subjects. Diabetologia. 2005;48(12):2631-2640.

(3.) Jocken et al. Effect of beta-adrenergic stimulation on whole-body and abdominal subcutaneous adipose tissue lipolysis in lean and obese men. Diabetologia. 2008;51(2).

(4.) Kraemer et al. Physiological responses to heavy weight training with short rest periods. Int J Sports Med. 1987;8(4):247-252.

(5.) Jost et al. Comparison of sympatho-adrenergic regulation at rest and of the adrenoceptor regulation at rest and of the adrenoceptor system in swimmers, long-distance runners, weight lifters, wrestlers and untrained men. Eur J Appl Physiol Occup Physiol. 1989;58(6):596-604.

(6.) lrving et al. Effect of exercise training intensity on abdominal visceral fat and body composition. Medicine and science in sports and exercise 2008;40(11):1863-1872.

(7.) Coker et al. Influence of exercise intensity on abdominal fat and adiponectin in elderly adults. Metabolic Syndr Relat Disord. 2009;7(4):363-368.

(8.) Yki-Jarvinen et al. Effects of body composition on insulin sensitivity. Diabetes. 1983;32:965-969.

(9.) Takala et al. Insulin action on heart and skeletal muscle glucose uptake in weight lifters and endurance athletes. Am J Physiol. 1999;276:e706-e711.

(10.) Tresierras et al. Resistance training in the treatment of diabetes and obesity. J Cardiopulm Rehabil Prev. 2009;29:67-75.

(11.) Schimtz et al. Strength training and adiposity in premenopausal women: strong, healthy, and empowered study. Am J Clin Nutr. 2007:86(3):566-572.

(12.) Ottoson et al. Effects of cortisol and growth hormone on lipolysis in human adipose tissue. J Endocrinol Metab. 2000;85(2):799-803.

(13.) De Pergola et al. The adipose tissue metabolism: role of testosterone and DHEA. Int J Obes Relat Metab Disord. 2000;24(S2):59-63.
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Author:Teta, Jade; Teta, Keoni
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:Feb 1, 2010
Words:1219
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