New Clues to Prevent Weight Regain
Len Kravitz, Ph.D.
Introduction
Cardiovascular exercise and resistance training are important components to successful weight management interventions. However, there is a complex and unclear relationship between exercise training during weight loss and the free-living energy expenditure AFTER weight loss (Hunter et al., 2015). Hunter and colleagues note some studies suggest people actually move less after weight loss, while other studies say there is no change. With this question unsolved, Hunter and researchers decided to investigate the effects of aerobic exercise, resistance training or no exercise during a low-calorie weight loss program, and determine its effect on activity-related energy expenditure and non-exercise activity thermogenesis (NEAT, which is often referred to as spontaneous movement). Side Bars 1& 2 further discuss the importance of NEAT for a person's metabolic health.
Methods
One hundred forty sedentary (no exercise for one year), overweight (BMI> 27 and <30 kg/m2) women (age = 20-44 yrs) volunteered for this study. After a 4-week weight stabilization period (participants provided daily meals during week 3 and 4), participants were divided into three groups: 1) weight loss with aerobic exercise training 3x/week (aerobic-and-diet group) 2) weight loss with resistance exercise 3x/week (resistance-and-diet group), and 3) weight loss with no exercise training (control group). All participants were provided an 800-kilocalorie diet until they reached a BMI <25 kg/m2, which took approximately 16 weeks for all 3 groups. The furnished diet macronutrient breakdown during the 16-week breakdown was 20-22% fat, 20-22% protein, 56-58% carbohydrate.
Aerobic Training Group
The aerobic training group participants completed 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 each week. By the 8th week of training the subjects were doing 40 minutes of aerobic exercise at 80% of their MHR, which they maintained for the remainder of the 16-week study.
Resistance Training Group
Participants in the resistance training group completed a one week familiarization of all of the exercises which included squats, leg extensions, leg curls, bicep curls, triceps extension, latissimus dorsi pull-downs, bench press, military press, low-back extension and bent-leg sit-ups. All participants then completed one repetition max testing (1RM) to determine the appropriate percent lifting capacity for each major exercise group. The participants began with one set of 10 repetitions at 65% of their 1RM, increasing gradually each week until subjects were training at 80% of their 1RM. On week 5 the participants began completing 2 sets of 10 repetitions at 80% of their 1RM (which they maintained for the duration of the study) and rested 2 minutes between sets. Muscular strength was re-evaluated every 5 weeks with appropriate load adjustments being made to sustain the 80% 1RM exercise intensity for major exercises.
No Exercise Group
The no exercise group served as the control group for this study. Participants were only provided an 800-kilocalorie diet and did no exercise.
Results and Discussion
All subjects in this 16-week study lost an average of 25 lbs on the 800 kilocalorie/day diet. The data indicate that the total daily energy expenditure decreased by 63 kcals/day in the aerobic-and-diet training group versus a decrease of 259 kcals/day in the no exercise group. The resistance-and-diet training group increased their total daily energy expenditure by 63 kcals/day. The activity-related energy expenditure increased by 13 kcals/day and 109 kcals/day for the aerobic training and resistance training groups, respectively. The no exercise group decreased their activity-related energy expenditure by 142 kcals/day. With NEAT, the aerobic training group showed a decrease of 87 kcals/day while the resistance training group had an increase in 61 kcals/day. The no exercise group had a decrease in 143 kcals/day in NEAT. Hunter and colleagues (2014) highlight that NEAT interventions are a primary strategy that helps individuals resist weight gain after a weight loss intervention. The importance of NEAT for metabolic health is further discussed in Side Bar 1 and Side Bar 2. Personal trainers clearly need to influence clients that moving more during the day is beneficial for weight loss, weight re-gain prevention and metabolic health.
The %fat loss in this 16-week intervention was 10.1%, 10.6%, 9.2% for the aerobic-and-diet, resistance-and-diet, and no exercise group, respectively. This shows that exercise is effective in promoting fat loss during a very low-calorie intervention (800 kcals/day)
Final Thoughts
The study results clearly show that exercise training is critical for maintaining NEAT and AEE following weight loss, and thus confirms what many personal trainers know from their experience; that persons who go on 'diet only' interventions are quite susceptible weight regain following the diet. The study also shows that resistance training is particularly important in a dietary weight loss intervention, as it appears to have a most beneficial effect in preventing weight regain.
Side Bar 1. Trainers Beware of the Active Couch Potato
Uniquely, some women and men can attain the public-health guidelines on physical activity and exercise, but if they sit for extended periods of time, their metabolic health is weakened (Owen et al. 2014). Owen et al. explain that these adults, who they identify as 'active couch potatoes', sit for prolonged periods of time every day (i.e., at a desktop workstation for instance). However they are still attaining their weekly 150 minutes of moderate-to-vigorous intensity exercise a week. The researchers' investigations show 'active couch potatoes' are susceptible to developing metabolic syndrome. Metabolic syndrome is a cluster of conditions including abdominal (or central) obesity, elevated blood pressure, elevated fasting plasma glucose, high serum triglycerides, and low high-density lipoprotein (HDL) levels. Metabolic syndrome is associated with the risk of developing cardiovascular disease (CVD) and diabetes, thus the connection is established with too much sitting and CVD. See Side Bar 2 for more on the risk of too much sitting.
Side Bar 2. Replacing Sitting Time With Physical Activity Reduces All Risks to Mortality
From the previous 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 yr of age), Mathews et al. show that greater sitting time (i.e., sitting for 12 or more hrs/day versus 5 or fewer hours/day) is associated to a 20%-40% increased risk of mortality from all causes and a 40-55% greater risk for cardiovascular mortality. The authors continue that including as much as 1 hour/day of NEAT (household chores, gardening, daily moving) is associated with a considerably lowered risk of mortality from all causes. Mathews et al. continue that 1-2 hours per day of NEAT is associated with a 30% reduction in mortality for men and a 50-60% reduction in women. The researchers highlight the time spent in sedentary behaviors has increased 43% the last 40 years in the U.S. The authors also note that public health strategies typically focus more on exercise and clearly need to be modified to focus as much on REDUCING sedentary behavior.
Below are 15 ways to help clients add more activity to their daily lives.
1. Take a walk break every time you take a coffee break
2. Take up gardening for a hobby
3. Take a walk after dinner when out with friends or home with family
4. Take a walk break after you eat lunch
5. Stand up and move whenever you take a drink of water at work
7. Get a pedometer 'app and strive for &Mac179; 10,000 steps day
8. Walk your dog daily
9. When watching TV, stand up and move every time a commercial comes on
10. Stop at the park on your way home from work and take a walk
11. Walk fast when doing errands
12. Walk up and down the shopping aisles at the store before you begin to shop
13. Walk to a co-worker's desk instead of emailing or calling her/him
14. Try interval walking; walk fast for short spurts interspersed with normal walking
15. After reading 4 pages of your current book get up and move a little
Source: Don't Sit, Get Fit
http://getfit.unm.edu/index.html
Accessed: September 27, 2015
@bio:Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, Albuquerque, where he won the Outstanding Teacher of the Year award. He has received the prestigious Can-Fit-Pro Lifetime Achievement Award and American Council on Exercise Fitness Educator of the Year.
Additional References:
Matthews, C.E., Moore, S.C., Sampson, J. et al. (2015). Mortality benefits for replacing sitting time with different physical activities. Medicine & Science in Sports and Exercise, 47(9), 1833-1840.
Owen, N., Healy, G.N., Matthews, C.E., et al. (2010) Too much sitting: The population-health science of sedentary behavior. Exercise and Sport Science Reviews. 38(3), 105-113.
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