Cardiovascular exercise and resistance training are essential to successful weight management. A study (Hunter et al. 2015) was done to investigate the effects of (1) aerobic exercise, (2) resistance training and (3) no exercise during a low-calorie weight loss program.
The study’s 140 volunteers were overweight women aged 20–44; none had exercised for a year and each had a BMI between 27 and 30. The women were divided into three groups:
- aerobic-and-diet training: weight loss with aerobic exercise three times per week
- resistance-and-diet training: weight loss with resistance exercise three times per week
- control: weight loss with no exercise training
All the women received an 800 calorie-per-day diet until their BMI fell below 25, which took approximately 16 weeks for all 3 groups.
The aerobic training group did supervised indoor walking and/or jogging, starting at 67% of maximum heart rate (MHR) for 20 minutes. Cardiovascular duration and intensity training increased gradually week by week. By the 8th week of training, the women were doing 40 minutes of aerobic exercise at 80% of their MHR, and they maintained this level for the rest of the 16-week study.
The resistance training group completed a 1-week familiarization of all of the exercises, which included leg extension, leg curl, squat, biceps curl, triceps extension, latissimus dorsi pull-down, bench press, military press, low-back extension and bent-leg sit-up. They began with 1 set of 10 repetitions at 65% of their 1-RM, increasing gradually each week until they were training at 80% of their 1-RM. On week 5, they began completing 2 sets of 10 repetitions at 80% of their 1-RM (which they maintained for the rest of the study).
The no-exercise group served as the control for this study. Participants consumed an 800-kcal-per-day diet and did no exercise.
All the women in this 16-week study lost an average of 25 pounds. Total daily energy expenditure decreased by 63 kcal per day in the aerobic-and-diet training group and fell by 259 kcal per day in the no-exercise group. The resistance-and-diet training group increased total daily energy expenditure by 63 kcal per day.
Activity-related energy expenditure increased by 13 kcal per day and 109 kcal per day for the aerobic training and resistance training groups, respectively. In the no-exercise group, activity-related energy expenditure decreased by 142 kcal per day (thus showing that people start to move less during low-kilocalorie interventions). The aerobic training group showed a decrease of 87 kcal per day, while the resistance training group had an increase of 61 kcal per day. The no-exercise group had a decrease of 143 kcal per day.
Hunter et al. 2015 remark that exercise training, particularly resistance training, increases daily energy expenditure by increasing muscle mass (muscle is very metabolically active tissue).
The percentage of fat loss in this 16-week intervention was 10.1% for the aerobic-and-diet training group, 10.6% for the resistance-and-diet training group and 9.2% for the no-exercise group. This shows that exercise promotes fat loss during a very low-calorie intervention (800 kcal per day).
The results of this study clearly show that exercise training is critical for maintaining activity-related energy expenditure after weight loss, and that people who go on diet-only interventions are quite susceptible to weight regain following the diet. The study also shows that resistance training is particularly important in a dietary weight loss intervention, as this type of exercise appears to do the most good in preventing weight regain.
For additional information: IDEA Health & Fitness Association