Want to lose weight? Better head to the gym—after all, that’s the best way to lose weight, right? In this month’s “Wellness Read,” we discuss how exercise can support your weight loss journey. Additionally, we discuss the overall impact of exercise on weight maintenance as well as other critical benefits it produces.
Given all the images we see in media of physically fit people pumping iron, running in idyllic surroundings, and sweating it out on bike or after a yoga class it seems that exercise is the key to losing weight and getting into great shape. According to the American Heart Association, the weekly target for moderate intensity aerobic activity is 75-150 minutes weekly, and yet even as we are starting to see more people take this message seriously obesity continues to grow (as well as its estimated $147B global economic burden).1 Some have suggested a few explanations2:
- People simply are not meeting activity recommendations
- This target for aerobic activity is insufficient for weight loss.
- Individuals who are achieving said targets are compensating by eating more.
Diving into this question, a 2018 review analyzed the adequacy of current physical activity guidelines for inducing clinically significant weight loss (~5-10% of total body weight). Most studies in the review conclude that exercise programs meeting national recommendations may lead to modest weight loss but are unlikely to affect significant weight loss. One study included in the review found the following:
- Study groups that increased their exercise target to achieve 75-150mins/week of exercise experienced modest, yet statistically insignificant weight loss.2
- Study groups that increased their exercise target to achieve 225-420mins/week of exercise experienced >5% change in weight. 2 (The American College of Sports Medicine currently recommends >225 minutes/week of exercise for individuals attempting to lose weight.2)
Clearly, activity alone is not enough to produce statistically significant weight changes for the average person. So, why isn’t exercise helping us lose more weight? Should we throw in the proverbial towel? The biggest problem: these studies do not consider diet.
Exercise contributes to energy output
Simply stated, to achieve weight loss one must be in an energy deficit.
Energy output > Energy input
Exercise increases energy output, which leads to an energy deficit, but we must also look at the other half of the energy expenditure equation (energy input). If the combination of exercise and dietary consumption does not lead to a calorie deficit, weight loss in generally healthy people is not possible.
The results of an 18-month participant study including exercise and dietary program interventions indicated:
- participants in an exercise only intervention group experienced weight loss of about 2%.2
- participants in a diet only intervention group experienced, on average, 9.5% weight loss.2
- participants in a combination of diet and exercise intervention group experienced, on average, 11.3% weight loss.2
These compelling findings confirm that weight loss is achieved when exercise and dietary changes are made.
Exercise preserves lean mass
When assessing the success of a weight loss approach, it is important to consider the type of weight lost. Weight alone is too general a measurement. It is important consider the proportion of fat to fat-free tissue in the body, more accurately represented as body fat percentage (BF%), a measure of body composition. In addition to contributing to energy output, exercise also plays a vital role in muscle mass gain and maintenance. Most diet-only weight loss interventions typically result in the loss of both fat and fat-free tissue.2,4,5 One study showed:
Exercise groups were the only groups to show lean muscle mass preservation, despite the statistically insignificant changes in weight when performing 75-150mins/week of moderate intensity exercise.4
As we age, muscle preservation becomes more critical as muscle mass naturally declines after the age of 30. Maintaining lean muscle is one of the best ways to preserve our metabolism, promote strength and mobility, and prevent chronic disease.5
exercise supports weight maintenance
While initially losing weight is a challenge, maintaining the weight loss is an even greater challenge for most people.. Based on the same research, keeping weight off largely depends on maintaining a consistent exercise routine.5 A meta-analysis that assessed various behavioral weight management programs concluded:
Individuals who combined diet and exercise experienced a 13.9 lbs. or greater weight loss at 12-18 months compared to the participants using diet-only interventions. 2
This supports the idea that exercise and nutrition both play essential roles in achieving sustainable weight loss over time.
Additional benefits of exercise
Why else should we keep up on our exercise routines? Well, when we meet the recommendation of 75-150 minutes of moderate intensity exercise each week, we generate a multitude of other positive health effects for ourselves:
- Reduced cardiovascular risk – improves the efficiency of the heart and lungs, increasing oxygen delivery and removing waste from the body.1,3
- Reduced diabetes risk – lowers blood glucose levels and improves insulin sensitivity.3
- Improved lipid profile – reduces plasma LDL-C, the bad cholesterol.3
- Decreased blood pressure – strengthens the heart helping to pump blood more efficiently, decreasing the force on your arteries.1,3
- Improved joint health and function – maintains strength of muscles around joints (and lubricates joints and reduces stiffness), decreasing bone loss as we age. 3,5
- Stress management – releases endorphins, which are your “feel good” receptors, to help calm the mind and enable easier navigation of stressors.3
- Improved cognitive functioning – boosts memory and cognitive functions by improving mood and sleep performance.3
There are various other health related benefits independent from weight loss, so even if you are not achieving an energy deficit and losing weight, it doesn’t mean that your hard work in the gym is in vain.
To summarize, exercise alone is not as effective as a dietary intervention and a combined approach is best for those seeking to lose weight (and keep it off), and exercise is the key factor in the redistribution of fat and fat-free mass in the body. Additionally, exercise provides innumerable benefits (regardless of its effect on weight) and is a great place to start when creating new habits aimed at a weight loss goal. When you get to that weight goal, routine exercise seems to be the key to keeping the weight off. So, the next time you start running for miles and miles or get back on the Peloton to knock off a couple pounds, don’t forget the important role of energy input in losing weight sustainably.
In Real Health,
Scott Schafer
Head of Fitness
References
- American Heart Association recommendations for physical activity in adults and kids. www.heart.org. (n.d.). from https://www.heart.org/en/healthy-living/fitness/fitness-basics/aha-recs-for-physical-activity-in-adults
- Swift, D. L., McGee, J. E., Earnest, C. P., Carlisle, E., Nygard, M., & Johannsen, N. M. (2018). The effects of exercise and physical activity on weight loss and maintenance. Progress in Cardiovascular Diseases, 61(2), 206–213. https://doi.org/10.1016/j.pcad.2018.07.014
- ACSM. (2017). ACSM’s resources for the Health Fitness Specialist. Wolters Kluwer.
- D’Souza, A. C., Lau, K. J., & Phillips, S. M. (2021). Exercise in the maintenance of weight loss: Health benefits beyond lost weight on the scale. British Journal of Sports Medicine. https://doi.org/10.1136/bjsports-2021-104754
- Foright, R. M., Presby, D. M., Sherk, V. D., Kahn, D., Checkley, L. A., Giles, E. D., Bergouignan, A., Higgins, J. A., Jackman, M. R., Hill, J. O., & MacLean, P. S. (2018). Is regular exercise an effective strategy for weight loss maintenance? Physiology & Behavior, 188, 86–93. https://doi.org/10.1016/j.physbeh.2018.01.025