In his New York Times bestselling book, Don’t Sweat the Small Stuff; author Richard Carlson encourages readers not to sweat the small stuff! That is good advice for our modern world. Today, I recommend “Sweat the Truth” when Strength Training! Despite our best intentions, getting pulled down rabbit holes that lead to nowhere is easy. Not long ago, I found myself wandering down one such rabbit hole. Advertisements from a local fitness center promoted an infrared sauna with revolutionary calorie-burning technology. According to the ad, a session (i.e., sitting in a sauna) burns up to 800 calories. Curious about the technology, I contacted the business promoting it. When I asked, “How is it possible to burn 800 calories while sitting in a sauna,” the person on the phone said they had researched the sauna online. Their research led them to believe calories get burned as sweat evaporates from the body. Unfortunately, their conclusions are incorrect.
Guyton’s textbook of medical physiology states that “as water evaporates from the body surface, 0.85 calories of heat are lost for each gram of water that evaporates”.[1] However, losing heat through the evaporation of sweat does not mean your body is burning calories. Sweating in a sauna occurs because your body absorbs heat, not because its burning calories. This process is called thermoregulation. It prevents heat illness by regulating body temperature. Thermoregulation, and the breakdown of chemical energy (burning calories), are two separate processes and not directly related. According to Walter Thompson, Ph.D. professor of exercise science at Georgia State University, “Sweating is how your body cools itself. Post-exercise weight loss often represents a loss of fluids, not a reduction of body fat”. In their highly acclaimed book The Fat-Free Truth, fitness authors Liz Neporent and Suzanne Schlosberg tackle this issue by telling readers, “Don’t confuse sweating with fat-burning.”[2] If it were possible to burn hundreds of calories while sitting in a sauna, you could expect to lose significant weight without moving your body or changing your diet. From a weight management standpoint, this would make healthy lifestyles (exercise and sensible eating) obsolete. This type of thinking goes against established principles of exercise science. In reality, improving body composition (reducing body fat and increasing muscle mass) requires a commitment to a healthy lifestyle!
The Federal Trade Commission warns consumers to avoid this no-effort approach to weight loss. Not surprisingly, there’s no evidence linking sauna use to fat loss. However, there is evidence showing the opposite! The Clinical Guidelines for Weight Loss and Weight Management from the National Institutes of Health (NIH) provide clear evidence of what works for weight loss and maintenance. A panel of 24 experts in medicine, clinical nutrition, exercise physiology, and psychology published a summary of the guidelines in the journal Obesity Research. The report reviewed evidence from nearly 400 published studies. It concluded that successful weight management is best achieved by participating in programs that focus on diet therapy, physical activity, and behavioral therapy. The NIH report does not mention or recommend saunas for weight loss.
You may wonder how a business gets away with such bold, unsubstantiated claims. Unfortunately, there are no “Standards of Practice” within the fitness industry. Advertising frequently comes down to saying whatever you want. The majority of the time, advertisement claims are not challenged. Ultimately, consumers suffer the most. Despite the availability of evidence-based guidelines (i.e., Physical Activity Guidelines for Americans, etc.), the Federal Trade Commission has limited funds to enforce Truth-In-Advertising laws. Fortunately, we’ve come a long way in combating exercise deception. Published research consistently shows intense, brief workouts (i.e., Strength Training) provide life-changing health benefits.[3] The Second Edition of the Physical Activity Guidelines for Americans recommends that all adults Strength Train weekly.[4] The best way to avoid Strength Training rabbit holes is to become an educated consumer.[4] Continue to learn, ask questions, and keep your thinking cap on!
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Stay Strong,
Richard J. Wolff, RDN
References
1. Arthur C. Guyton, M.D., 1971, Textbook of Medical Physiology. W. B. Saunders Company. Philadelphia, PA.
2. Neporent, L., Schlosberg, S., 2005. The Fat-Free Truth. New York, NY. Houghton Mifflin Company
3. Physical Activity Guidelines for Americans. https://health.gov/paguidelines/
4. Evidence-Based Resistance Training Recommendations. Medicina Sportiva. Med Sport 15 (3): 147-162, 2011. DOI: 10.2478/v10036-011-0025-x.