Hunter, G.R., et al. 2015. Exercise training and energy expenditure following weight loss.
Medicine
&
Science in Sports
&
Exercise, 47 (9), 1950–57.

Introduction

Cardiovascular exercise and resistance training are essential to successful weight management. However, there is a complex, unclear relationship between exercise training during weight loss and free-living energy expenditure after weight loss (Hunter et al. 2015).

Some earlier studies have suggested that people move less after weight loss, while others have found no change. This unsolved mystery motivated Hunter and fellow researchers to investigate the effects of (1) aerobic exercise, (2) resistance training and (3) no exercise during a low-calorie weight loss program, and to determine the impact of each on activity-related energy expenditure and nonexercise activity thermogenesis (NEAT, often called spontaneous movement).

Study Methods

The study’s 140 volunteers were overweight women aged 20–44; none had exercised for a year and each had a body mass index between 27 and 30. After a 4-week weight stabilization period (with daily meals provided in weeks 3 and 4), 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-kilocalorie-per-day diet until their BMI fell below 25, which took approximately 16 weeks for all 3 groups. The furnished diet’s macronutrient breakdown was 20%–22% fat, 20%–22% protein and 56%–58% carbohydrate.


Aerobic Training

The aerobic training group did supervised indoor walking and/or jogging, starting at 67% of maximum heart rate (MHR) for 20 minutes. MHR was determined from a graded maximal aerobic capacity exercise test. 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.


Resistance Training

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.

All the women then completed 1-repetition-maximum (1-RM) testing to determine the appropriate percent of lifting capacity for each major exercise group. 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), resting 2 minutes between sets. Muscular strength was reevaluated every 5 weeks, and loads were adjusted to sustain the 80% of 1-RM exercise intensity for major exercises.


No Exercise

The no-exercise group served as the control for this study. Participants consumed an 800-kcal-per-day diet and did no exercise.

Results and Discussion

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). With NEAT, 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 for NEAT. The dramatic drop in total daily energy expenditure in the no-exercise group, as contrasted with the aerobic-and-diet and resistance-and-diet training groups (see Table 1), is very meaningful information for personal trainers to share with clients.

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). In addition, they explain that postexercise oxygen consumption (EPOC) contributes to the body’s total daily energy expenditure.

NEAT (nonexercise movement) interventions can be a primary strategy for helping people avoid weight gain after a weight loss intervention, say Hunter and colleagues. The importance of NEAT for metabolic health is further discussed in the sidebars. Personal trainers clearly need to persuade clients that moving more during the day will help them lose weight, prevent weight regain and sustain their metabolic health.

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).

Final Thoughts

The results of this study clearly show that exercise training is critical for maintaining NEAT and activity-related energy expenditure after weight loss, and thus they confirm what many personal trainers know from experience—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.

Table 1.

table

Replacing Sitting Time With Physical Activity Reduces All-Cause Mortality Risk

From previously reported research on weight regain after weight loss, Hunter et al. note the importance of daily movement (NEAT) for the prevention of weight regain. In a rather large prospective 7-year study with 154,614 men and women (59-82 years old), Matthews et al. show that more sitting (e.g., sitting for 12 or more hours per day vs. 5 or fewer hours per day) is associated with a 20%-40% higher risk of mor- tality from all causes and a 40%-55% higher risk for cardiovascular mortality.By contrast, as much as 1 hour per day of NEAT (household chores, gardening, daily moving) is associated with a considerably lower risk of mortality from all causes, according to Matthews et al. And 1-2 hours per day of NEAT is associated with a 30% reduction in mortality for men and a 50%-60% reduction in women.

Matthews et al. say that time spent in sedentary behaviors has increased 43% in the U.S. over the last 40 years, and they note that public health strategies typically focus more on exercise and clearly need to be modified to focus as much on reducing seden- tary behavior. Below are some ways to help clients add more activity to their daily lives.

  • Take a walk break every time you take a coffee break.
  • Take up gardening as a hobby.
  • Take a walk after dinner when out with friends or home with family.
  • Take a walk break after you eat lunch.
  • Stand up and move whenever you take a drink of water at work.
  • Get a pedometer app and strive for ÔëÑ 10,000 steps day.
  • Walk your dog daily.
  • When watching TV, stand up and move when a commercial comes on.
  • Stop at the park on your way home from work and take a walk.
  • Walk fast when doing errands.
  • Walk up and down the shopping aisles at the store before you begin to shop.
  • Walk to a coworker’s desk instead of emailing or calling.
  • Try interval walking; walk fast for short spurts interspersed with normal walking.
  • After reading four pages of your current book get up and move a little.

Source: Don’t Sit, Get Fit, http://getfit.unm.edu/index.html.

Active Couch Potatoes, Beware

Adults who sit for extended periods can weaken their metabolic health even if they meet the public health guidelines for physical activity and exercise (Owen et al. 2010). Owen et al. explain that “active couch potatoes” achieve their weekly 150 minutes of moderate- to vigorous-intensity exercise each week, but they still sit for prolonged periods every day (at a desktop workstation, for instance).

The researchers’ investigations show that these adults are susceptible to metabolic syndrome–a cluster of conditions including abdominal (or central) obesity, elevated blood pressure, elevated fasting plasma glucose,high serum triglycerides and low levels of HDL cholesterol. Metabolic syndrome is associated with the risk of developing cardiovascular disease (CVD) and diabetes–hence the connection between CVD and too much sitting.


References

Matthews, C.E., et al. 2015. Mortality benefits for replacing sitting time with different physical activities. Medicine & Science in Sports & Exercise, 47 (9), 1833-40.
Owen, N., et al. 2010. Too much sitting: The population-health science of sedentary behavior. Exercise and Sport Science Reviews, 38 (3), 105-13.

Len Kravitz, PhD

Len Kravitz, PhD is a professor and program coordinator of exercise science at the University of New Mexico where he recently received the Presidential Award of Distinction and the Outstanding Teacher of the Year award. In addition to being a 2016 inductee into the National Fitness Hall of Fame, Dr. Kravitz was awarded the Fitness Educator of the Year by the American Council on Exercise. Just recently, ACSM honored him with writing the 'Paper of the Year' for the ACSM Health and Fitness Journal.

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