The Role of Exercise in Weight Management

Last week we discussed the pros and cons of intermittent fasting as a tool in weight management. Like other weight loss methods, intermittent fasting only works if followed. And it's not meant for everyone. While this method of dieting may be controversial to some, exercise is the second step in weight control. No one can deny the psychological and physical benefits of exercise. Regular physical exercise aids in stress reduction, blood sugar control, cholesterol reduction, and improved sleep. It’s also beneficial for weight control.Aerobic exercise (walking, jogging, swimming, cycling) uses glucose (from glycogen) and triglycerides (from fat in storage) for energy. Strength or resistance training helps build muscle, which is more metabolic at rest than fat tissue. Both are beneficial to weight management.According to the 2018 Physical Activity Guidelines for Americans, Americans are advised to do a minimum of 30 minutes of physical activity most days of the week. This equates to 150 minutes of moderate activity or 75 minutes of vigorous exercise per week for general health. This should include both aerobic and strength training exercises. However, without calorie restriction, this isn’t enough for weight loss or weight maintenance in most people.Currently, 53 % of Americans over 18 do adequate aerobic exercise while only 23% get both aerobic and muscle-strengthening activity. Most US adults are still too sedentary. A sedentary lifestyle is associated with cardiovascular disease, type 2 diabetes, and certain types of cancer including endometrial, colon, and lung cancer.Which types of exercise aid in weight control? How much should I do?In addition to caloric restriction, both aerobic and strength training is beneficial for weight control. The ACSM (American College of Sports Medicine) advises 200-300 minutes of moderate-intensity exercise to lose weight and sustain the loss. Moderate-intensity exercises include brisk walking, jogging, using a rowing machine, or doing a 50-60 minute dance class. To judge the level of intensity you should aim for, think of it this way: a person should be able to carry a conversation but not be able to sing.HIIT (high-intensity interval training) is one method of exercise that may be beneficial to those who are trying to lose weight and are short on time. One way to do HIIT involves doing high-intensity exercise (such as sprinting) for 60 seconds followed by 60 seconds of low-intensity exercise (walking) or rest. Exercises are repeated 8 times with rest for a few minutes, then repeated until 30 minutes of exercise is completed.A meta-analysis of 39 studies with 671 participants showed that HIIT reduced total, abdominal, and visceral fat mass in both men and women aged 38.8 +/- 14.4. Running was more effective than cycling in lowering total and visceral fat mass while low-intensity exercise (like walking) also resulted in abdominal and visceral fat loss. The latter took more time. HIIT training is typically done a few days a week. Individuals are advised to choose less intense exercises in between HIIT training days.More muscle matters!One of the biggest reasons (no pun intended) that adults gain weight over time is due to muscle loss. A comparison study of various methods of exercise was performed with older subjects with obesity. Subjects got randomly assigned to a weight control program along with one of four programs: aerobic training, resistance training, combined aerobic and resistance training, or a control group (no treatment).The initial outcome was the change in Physical Performance Test Scores from the start to 6 months after the study began, while secondary outcomes included changes in body composition, bone mineral density, and physical function.There were 141 total subjects that finished the study. Physical Performance Test score was higher in the combination group than in the aerobic and resistance groups. Bodyweight decreased in all exercise groups (9%) but not in the control group.Lean mass and bone density were maintained the most in the combination and resistance groups. Strength also increased in the resistance training and combination training groups. As muscle is more metabolic than fat, maintaining muscle mass is important to long-term weight control.It’s important for individuals who have been sedentary to check with their doctors before embarking on a new exercise program. While HIIT training may be appropriate for younger individuals and/or those without comorbidities like cardiovascular disease, it’s important to find an exercise that’s enjoyable.Physical activities to suggest to your clients could include:

• Multiple bouts of moderately paced walking a few times per day.
• Use of an elliptical or rowing machine or a water aerobics class
• A walking video to use at home
• Playing tennis or pickleball
• Trying a regular or stationary bike or a spin class
• Joining a kickboxing or Zumba class at a gym or rec center

Resistance training may include:

• Use of stretch bands
• Multiple reps of small hand weights
• Use of nautilus machines
• A pilates class (in person or at home)

By Lisa Andrews, MEd, RD, LDPDF Handout: Exercise and WeightReferences:

1. Physical Activity Guidelines for Americans, 2nd edition (health.gov)
2. Katzmarzyk PT, Powell KE, Jakicic JM, Troiano RP, Piercy K, Tennant B; 2018 PHYSICAL ACTIVITY GUIDELINES ADVISORY COMMITTEE*. Sedentary Behavior and Health: Update from the 2018 Physical Activity Guidelines Advisory Committee. Med Sci Sports Exerc. 2019 Jun;51(6):1227-1241
3. Physical Activity Guidelines Resources (acsm.org)
4. Wewege M, van den Berg R, Ward RE, Keech A. The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obes Rev. 2017 Jun;18(6):635-646.
5. Maillard F, Pereira B, Boisseau N. Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis. Sports Med. 2018 Feb;48(2):269-288.
6. Villareal DT, Aguirre L, Gurney AB, Waters DL, Sinacore DR, Colombo E, Armamento-Villareal R, Qualls C. Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults. N Engl J Med. 2017 May 18;376(20):1943-1955