Is Exercising More the Best Way to Lose Fat? Insights from Twins Research Summary
- Seven pairs of young adult male identical twins maintained the same calories and nutrient intake while exercising more for 2 hours a day. The exercise was on cycle ergometers twice daily (i.e., 1 hour each session) for 93 days. The energy deficit (i.e., calories burned) caused by exercise was 1000 calories daily.
- The average weight loss was 11 pounds; furthermore, this was entirely from fat mass, while fat-free mass remained unchanged.
- Despite eating the same diet and exercising the same amount, the twins did not lose the same weight (i.e., some lost more weight than their siblings). The study results challenge the notion that identical calorie deficits and calories burned yield similair weight loss.
DO I NEED TO EXERCISE MORE FOR FAT LOSS?
Exercising more is often believed to be a key strategy for achieving and maintaining weight loss in the long term. However, the notion that simply exercising more will result in more fat loss is overly simplistic and often ineffective. Ask the typical American how to lose fat, and most will say, “You Need to Exercise More!” While exercise has numerous health benefits and is an essential component of a healthy lifestyle, its direct impact on long-term weight loss maintenance is not as straightforward as previously thought. Not surprisingly, starting an exercise program can result in weight loss, but keeping it off is a different story. Most studies have found that exercise is more beneficial for weight maintenance than long-term weight loss. (Johansson et al., 2014; Swift et al., 2014)
Best Exercise to Lose Weight
Exercising more will help you lose weight, but it leads to less weight loss than you would think. Moreover, gyms and fat-burning programs love to say they burn over 1000 calories per workout, but burning 1000 calories per workout is no easy task. However, if you did this over 3 months, how much weight would you expect to lose? Most people would say 20 pounds; however, it’s not as much as you think. A study conducted back in 1994 on identical twins had them burn 1000 calories a day through exercise and provides compelling insights that excising will undoubtedly help you lose fat, but it’s a lot less than you would think. (Bouchard et al., 1994)
Why Use Identical Twins in a Study on Exercising More?
First, why use identical twins in a study? Well, it would be assumed that if identical twins ate the same diet and burned the same calories through exercise, given their identical genes, they should both equally lose the same amount of weight. Surprisingly, that’s not what this study finds, and this study also challenges the conventional wisdom of the energy deficit model, where exercising more should result in continuous weight loss. This study is interesting because the twins experienced varied weight loss outcomes despite identical genes and calorie intake, suggesting other factors at play.
Review of the Literature: Using More Exercise to Lose Weight
Traditional guidelines recommend burning 3500 calories to lose 1 lb. of fat, but real-world outcomes often differ. The 3500-calorie rule originates from early research on calorie content in fat tissue. They would put fat content in a device that measures how many units of energy (i.e., calories burned) it takes to melt that pound of fat.
Nevertheless, despite its simplicity and widespread use in diet planning, recent studies suggest that this rule oversimplifies a complex biological process. Factors such as individual metabolic rate, body composition changes (i.e., losses in lean muscle), and physiological adaptations (i.e., changes in leptin and other hormones) play significant roles in actual weight loss outcomes. For example, studies have shown that weight loss through exercising more is often less than expected due to compensatory mechanisms, such as increased appetite and decreased movement in daily life or what is referred to as non-exercise activity thermogenesis (NEAT).(Church et al., 2009; King et al., 2008) (Merritt, 2021)
Importance of the Standard Energy Deficit
Indeed, ask any personal trainer about the best method for losing body fat, and they should all respond with ‘create an energy deficit.’ When people say ‘energy deficit,’ they mean reducing the number of calories consumed (creating a caloric deficit through a reduced-calorie diet). However, a calorie deficit can be achieved by manipulating the energy expenditure (the ‘Calories Out’ component of the energy balance equation).
Furthermore, several studies and reviews in the literature suggest that while exercising more is commonly recommended for weight management, its effectiveness in achieving long-term weight loss is limited. Multiple studies indicate dietary changes are more effective than exercise for fat loss. The POUNDS LOST study demonstrated that dietary adherence and changes in calorie-rich food significantly impact weight loss compared to exercise alone. The study finds that participants who focused on nutritional changes lose more weight than those who primarily increased their exercise levels.(Miketinas et al., 2017)
Another consideration is that the body adapts to increased exercise by becoming more efficient, which can lead to a plateau in weight loss. The body’s metabolic rate adjusts in response to sustained exercise, diminishing the expected weight loss benefits over time. This adaptation makes it challenging to continue losing weight through exercise alone. Merritt (2021)
Overview of the Study Protocol
The study involves seven pairs of sedentary young male identical twins housed in a controlled environment with a constant energy intake (i.e., the twins consume the same calories, protein, fat, and carbohydrates). Participants undergo a 93-day exercise regimen, performing twice-daily sessions on cycle ergometers. The exercise is designed to create an energy deficit of approximately 1000 calories per day by exercising more. Body composition and metabolic rates were meticulously measured throughout the study (Bouchard et al., 1994).
Results of the 2 Hours of More Exercise Each Day
The study found an average weight loss of 5.0 kg or 11 pounds, entirely from fat, with no change in fat-free mass. Significant subcutaneous and abdominal visceral fat reductions and increased lipid oxidation during exercise were observed. Notably, the twins had substantial intrapair differences in weight loss despite identical conditions (Bouchard et al., 1994). These findings suggest that genetic factors significantly influence individual responses to exercise and energy deficits. On average, the subjects lost about 5% body fat, starting the study with 23.6% and ending with 18.8%.
Discussion on How More Exercise Results is Different Weight Loss
The results challenge the notion that identical calorie deficits yield uniform weight loss. This aligns with other research, suggesting a more complex understanding of weight loss mechanisms rather than strictly “calories in” and “calories out.” The twins who exercised more had dramatic fat loss, but the results were not identical despite being twins. For instance, some individuals may experience greater reductions in visceral fat, which has been linked to improved metabolic health, while others may not respond as strongly. (Ravussin et al., 1988)
Individual variability in weight loss is evident in this study as participants followed identical diets and exercise routines but experienced different weight loss outcomes. A similar study found significant differences in weight loss among participants despite them following the same exercise program. Some participants lost a substantial amount of weight, while others lost little to none, highlighting the role of individual metabolic and hormonal responses. (King et al., 2008)
Debunking the 3500-Calorie Rule: Inconsistent Weight Loss Outcomes
The 3500-calorie rule, which posits that a deficit of 3500 calories will result in the loss of one pound of fat, does not account for the complex physiological changes that occur during weight loss. Research has shown that weight loss is not a linear process and that the 3500-calorie rule is an oversimplification. For instance, some individuals may not lose weight as expected due to metabolic adaptations that decrease the number of calories burned at rest.(Ravussin et al., 1988) Long-term studies have further debunked the 3500-calorie rule by showing that weight loss plateaus over time, even with continued caloric restriction. This plateau occurs because the body’s metabolism slows down in response to sustained energy deficits, making it increasingly difficult to lose additional weight.(Fothergill et al., 2016) Many people have often experienced this plateau in weight despite maintaining a reduced-calorie diet and exercising more.
Practical Weight Loss Tips:
Focus on a balanced, sustainable diet rather than extreme calorie deficits. Individual responses to dietary interventions can vary widely due to genetic factors (Bouchard et al., 1994). Prioritizing consistent exercise over an extreme more exercise is a better approach. Consistency in training is key to long-term weight management (King et al., 2007; Church et al., 2009). By integrating these insights, individuals can adopt more effective and personalized strategies for achieving their weight loss goals.
References
Bouchard, C., Tremblay, A., Després, J. P., Thériault, G., Nadeau, A., Lupien, P. J., Moorjani, S., Prudhomme, D., & Fournier, G. (1994). The response to exercise with constant energy intake in identical twins. Obes Res, 2(5), 400-410. https://doi.org/10.1002/j.1550-8528.1994.tb00087.x
Church, T. S., Martin, C. K., Thompson, A. M., Earnest, C. P., Mikus, C. R., & Blair, S. N. (2009). Changes in weight, waist circumference and compensatory responses with different doses of exercise among sedentary, overweight postmenopausal women. PLoS One, 4(2), e4515. https://doi.org/10.1371/journal.pone.0004515
Fothergill, E., Guo, J., Howard, L., Kerns, J. C., Knuth, N. D., Brychta, R., Chen, K. Y., Skarulis, M. C., Walter, M., Walter, P. J., & Hall, K. D. (2016). Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity (Silver Spring), 24(8), 1612-1619. https://doi.org/10.1002/oby.21538
Johansson, K., Neovius, M., & Hemmingsson, E. (2014). Effects of Anti-Obesity Drugs, Diet, and Exercise on Weight-Loss Maintenance After a Very-Low-Calorie Diet or Low-Calorie Diet: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. American Journal of Clinical Nutrition, 99(1), 14-23. https://doi.org/10.3945/ajcn.113.070052
King, N. A., Hopkins, M., Caudwell, P., Stubbs, R. J., & Blundell, J. E. (2008). Individual variability following 12 weeks of supervised exercise: identification and characterization of compensation for exercise-induced weight loss. Int J Obes (Lond), 32(1), 177-184. https://doi.org/10.1038/sj.ijo.0803712
References
Merritt, E. K. (2021). Why is it so hard to lose fat? Because it has to get out through your nose! An exercise physiology laboratory on oxygen consumption, metabolism, and weight loss. Advances in physiology education, 45 3, 599-606.
Miketinas, D. C., Bray, G. A., Sacks, F. M., & Champagne, C. M. (2017). Fiber Intake, Dietary Energy Density, and Adherence to Diet Assignment are Positively Associated with Weight‐Loss in Free‐Living Adults Consuming Calorie‐Restricted Diets at 6‐Month Follow‐Up: The POUNDS LOST Study. The FASEB Journal, 31.
Ravussin, E., Lillioja, S., Knowler, W. C., Christin, L., Freymond, D., Abbott, W. G., Boyce, V., Howard, B. V., & Bogardus, C. (1988). Reduced rate of energy expenditure as a risk factor for body-weight gain. N Engl J Med, 318(8), 467-472. https://doi.org/10.1056/nejm198802253180802
Swift, D. L., Johannsen, N. M., Lavie, C. J., Earnest, C. P., & Church, T. S. (2014). The Role of Exercise and Physical Activity in Weight Loss and Maintenance. Progress in Cardiovascular Diseases, 56(4), 441-447. https://doi.org/10.1016/j.pcad.2013.09.012
