NEW STUDY: INTERMITTENT FASTING CAUSES MUSCLE LOSS

By Steve Blechman

We all know that obesity is an independent risk factor from the coronavirus and severe illness. Now research has shown that just being overweight, not obese, can result in severe illness and even death! Intermittent fasting, often referred to as time-restricted eating, has become the latest diet craze not only for weight loss, but also for enhancing health.

Everyone from well-known celebrities to everyday, average people are trying it and claiming it is successful. Caloric restriction and intermittent fasting have been practiced for decades. It has gained popularity due to a growing body of research. Over the years, this research has shown that intermittent fasting and caloric restriction can enhance weight loss, cognitive function and help prevent heart disease, cancer and diabetes. It can also slow down the aging process and enhance longevity, but most of the research has been done on mice and rhesus monkeys, and not humans. A review and meta-analysis of intermittent fasting often referred to as time-restricted feeding (TRF) showed that it had a very positive effect on bodyweight and metabolism! But a commonly asked question remains: does intermittent fasting cause muscle loss? We will get more into the study below on the relationship between intermittent fasting, muscle loss and fat loss.

A new long-term study published in the December 2021 issue of the journal Medicine & Science in Sports & Exercise reported that a time-restricted eating program helped strength-training men lose weight, body fat and lower inflammation. Unfortunately, the strength-training participants lost muscle because their testosterone levels were lowered. The study was performed by researchers from institutions from Texas and Italy.

The study is very significant because it is the longest study of its kind on time-restricted eating. “The experiment was a single-blind, randomized study. Twenty healthy subjects were enrolled and underwent 12 months of either a time-restricted eating (TRE) diet or a normal diet (ND) protocol along with resistance training.” The subjects were young males in their 20s that had been weight training for at least five years prior to the study.

Antonio Paoli, MD who led the study said, “These findings demonstrated that well-trained resistance exercisers who would adhere to a fasting protocol for a long period of time can obtain beneficial effects on health biomarkers and inflammatory indices. Moreover, the long-term time-restricted eating approach spontaneously reduced the total caloric intake, driving a healthy weight loss. However long-term, time-restricted eating negatively effected muscle mass due to the significant negative impact reported on anabolic hormones in the population.”

A meta-analysis was published December 6, 2019, in the journal Reviews in Endocrine and Metabolic Disorders. The present systematic review and meta-analysis summarized the most recent evidence on the effect of time-restricted feeding (TRF) on weight loss and cardiometabolic variables in comparison with unrestricted time regimens. A total of 11 studies, 5 randomized controlled trials and 6 observational, were included. The findings of this important meta-analysis found greater weight loss with TRF than control regimens. There was also a significant reduction in fasting glucose and better blood sugar control in the TRF followers.

In a study in the prestigious journal JAMA Internal Medicine on September 28, 2020, researchers questioned, “What is the effect of time-restricted eating on weight loss and metabolic health in patients with overweight and obesity?” The researchers’ findings acknowledge, “In this prospective randomized clinical trial that included 116 adults with overweight or obesity, time-restricted eating was associated with a modest decrease (1.17%) in weight that was not significantly different from the decrease in the control group (0.75%).” Meaning that during the 3 months study on a daily 16-hour-fast (eating all their meals between noon and 8:00 pm), participants only lost 2 to 3 pounds, slightly better than their control group. The most concerning finding of the study was that 65% of weight loss from the fasting group was not fat but from lean body mass and muscle. A healthy weight loss is a diet that enhances body fat loss and not muscle and lean body mass. Having more muscle increases metabolism and helps you burn more calories over a 24-hour period. The researchers acknowledged that doing resistance training and eating more protein during the day may help prevent loss of muscle and lean body mass when practicing time-restricted fasting daily.

In conclusion, the recent and most significant study reported in the journal Medicine & Science in Sports & Exercise found that long-term intermittent fasting can cause severe muscle loss! Like I mentioned earlier, a healthy weight loss is a diet that enhances fat loss and not loss of lean body mass or muscle. Long-term intermittent fasting is not practical for bodybuilders or strength athletes who are striving to maximize their muscle mass.

References:

1. Moro, Tatiana1; Tinsley, Grant2; Pacelli, Francesco Q.1; Marcolin, Giuseppe1; Bianco, Antonino3; Paoli, Antonio1. Twelve Months of Time-restricted Eating and Resistance Training Improves Inflammatory Markers and Cardiometabolic Risk Factors, Medicine & Science in Sports & Exercise: December 2021 - Volume 53 - Issue 12 - p 2577-2585  doi:10.1249/MSS.0000000000002738

2. Lowe DA, Wu N, Rohdin-Bibby L, Moore AH, Kelly N, Liu YE, Philip E, Vittinghoff E, Heymsfield SB, Olgin JE, Shepherd JA, Weiss EJ. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med. 2020 Sep 28:e204153. doi: 10.1001/jamainternmed.2020.4153. Epub ahead of print, published online. PMID: 32986097; PMCID: PMC7522780.

3. Nakeshbandi M, Maini R, Daniel P, Rosengarten S, Parmar P, Wilson C, Kim JM, Oommen A, Mecklenburg M, Salvani J, Joseph MA, Breitman I. The impact of obesity on COVID-19 complications: a retrospective cohort study. Int J Obes (Lond). 2020 Sep;44(9):1832-1837. doi: 10.1038/s41366-020-0648-x. Epub 2020 Jul 25, published online. PMID: 32712623; PMCID: PMC7382318.

4. Marianna, P., Iolanda, C., Andrea, E. et al. Effects of time-restricted feeding on body weight and metabolism. A systematic review and meta-analysis. Rev Endocr Metab Disord (December 6, 2019). https://doi.org/10.1007/s11154-019-09524-w

5. Kesztyüs, D.; Cermak, P.; Gulich, M.; Kesztyüs, T. Adherence to Time-Restricted Feeding and Impact on Abdominal Obesity in Primary Care Patients: Results of a Pilot Study in a Pre-Post Design. Nutrients, November 21, 2019, 11, 2854.

6. Arefe Parvaresh, Roghaye Razavi, Behnood Abbasi, Khadijeh Yaghoobloo, Akbar Hassanzadeh, Noushin Mohammadifard, Sayyed Morteza Safavi, Amir Hadi, Cain C.T. Clark. Modified alternate-day fasting vs. calorie restriction in the treatment of patients with metabolic syndrome: A randomized clinical trial. Complementary Therapies in Medicine. https://doi.org/10.1016/j.ctim.2019.08.021. Published online August 28, 2019. Print: December 2019

7. Hunter S Waldman, Liliana I Renteria, Matthew J McAllister. Time-restricted feeding for the prevention of cardiometabolic diseases in high-stress occupations: a mechanistic review, Nutrition Reviews, November 27, 2019, nuz090, https://doi.org/10.1093/nutrit/nuz090

8. Ravussin, E., Beyl, R.A., Poggiogalle, E., Hsia, D.S. and Peterson, C.M. (2019), Early Time‐Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity, 27: 1244-1254. doi:10.1002/oby.22518

9. Anton SD, Lee SA, Donahoo WT, et al. The Effects of Time Restricted Feeding on Overweight, Older Adults: A Pilot Study. Nutrients, 2019;11(7):1500. Published 2019 Jun 30. doi:10.3390/nu11071500

10. Amandine Chaix, Emily N.C. Manoogian, Girish C. Melkani, Satchidananda Panda. Time-Restricted Eating to Prevent and Manage Chronic Metabolic Diseases. Annual Review of Nutrition 2019 39:1, 291-315

11. Templeman, I., Gonzalez, J., Thompson, D., & Betts, J. (n.d.). The role of intermittent fasting and meal timing in weight management and metabolic health. Proceedings of the Nutrition Society, 1-12. doi:10.1017/S0029665119000636

12. Paoli A, Tinsley G, Bianco A, Moro T. The Influence of Meal Frequency and Timing on Health in Humans: The Role of Fasting. Nutrients. 2019;11(4):719. Published 2019 Mar 28. doi:10.3390/nu11040719

13. Malinowski B, Zalewska K, Węsierska A, et al. Intermittent Fasting in Cardiovascular Disorders-An Overview. Nutrients, 2019;11(3):673. Published 2019 Mar 20. doi:10.3390/nu11030673

14. Baik, S‐H, Rajeev, V, Fann, DY‐W, Jo, D‐G, Arumugam, TV. Intermittent fasting increases adult hippocampal neurogenesis. Brain Behav, 2019; 00:e01444. https://doi.org/10.1002/brb3.1444

15. Trepanowski JF, Kroeger CM, Barnosky A, Klempel MC, Bhutani S, Hoddy KK, Gabel K, Freels S, Rigdon J, Rood J, Ravussin E, Varady KA. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance and Cardioprotection Among Metabolically Healthy Obese Adults - A Randomized Clinical Trial. JAMA Intern Med 2017;177(7):930-938. doi:10.1001/jamainternmed.2017.0936

16. Alternate-day fasting in non-obese subjects: effects on body weight, body composition, and energy metabolism. American Journal of Clinical Nutrition, January 2005.

17. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database of Systematic Reviews and Implementation Reports, February 2018.

18. Metabolic Effects of Intermittent Fasting. Annual Review of Nutrition, August 2017.

19. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism, May 2018.

20. Effect of Distinct Lifestyle Interventions on Mobilization of Fat Storage Pools: The CENTRAL MRI Randomized Controlled Trial. Yftach Gepner, Ilan Shelef, Dan Schwarzfuchs, Hila Zelicha, Lilac Tene, Anat Yaskolka Meir, Gal Tsaban, Noa Cohen, Nitzan Bril, Michal Rein, Dana Serfaty, Shira Kenigsbuch, Oded Komy, Arik Wolak, Yoash Chassidim, Rachel Golan, Hilla Avni-Hassid, Avital Bilitzky, Benjamin Sarusi, Eyal Goshen, Elad Shemesh, Yaakov Henkin, Michael Stumvoll, Matthias Blüher, Joachim Thiery, Uta Ceglarek, Assaf Rudich, Meir J. Stampfer and Iris Shai. Circulation 2017;CIRCULATION AHA.117.030501, 2017.

21. Suleiman Furmli, Rami Elmasry, Megan Ramos, Jason Fung. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Reports, 2018; bcr-2017-221854 DOI: 10.1136/bcr-2017-221854.

22. Sharayah Carter et al. Effect of Intermittent Compared With Continuous Energy Restricted Diet on Glycemic Control in Patients With Type 2 Diabetes, JAMA Network Open (2018). DOI: 10.1001/jamanetworkopen.2018.0756

23. Monique Tello, MD, MPH. Intermittent fasting: Surprising update June 29, 2018. https://www.health.harvard.edu/blog/intermittent-fasting-surprising-update-2018062914156

24. Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet. Iris Shai, R.D., Ph.D., Dan Schwarzfuchs, M.D., Yaakov Henkin, M.D., Danit R. Shahar, R.D., Ph.D., Shula Witkow, R.D., M.P.H., Ilana Greenberg, R.D., M.P.H., Rachel Golan, R.D., M.P.H., Drora Fraser, Ph.D., Arkady Bolotin, Ph.D., Hilel Vardi, M.Sc., Osnat Tangi-Rozental, B.A., Rachel Zuk-Ramot, R.N., Benjamin Sarusi, M.Sc., Dov Brickner, M.D., Ziva Schwartz, M.D., Einat Sheiner, M.D., Rachel Marko, M.Sc., Esther Katorza, M.Sc., Joachim Thiery, M.D., Georg Martin Fiedler, M.D., Matthias Blüher, M.D., Michael Stumvoll, M.D., and Meir J. Stampfer, M.D., Dr.P.H., for the Dietary Intervention Randomized Controlled Trial (DIRECT) Group N Engl J Med 2008; 359:229-241July 17, 2008 DOI: 10.1056/NEJMoa0708681

25. David S Ludwig. The Ketogenic Diet: Evidence for Optimism but High-Quality Research Needed, The Journal of Nutrition, nxz308, https://doi.org/10.1093/jn/nxz308

26. Ludwig DS, Ebbeling CB. The carbohydrate-insulin model of obesity: beyond “calories in, calories out.” JAMA Intern Med, 2018;178(8):1098-103.

27. Mansoor N, Vinknes KJ, Veierod MB, Retterstol K. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. Br J Nutr, 2016;115(3):466-79.

28. Ebbeling CB, Feldman HA, Klein GL, Wong JMW, Bielak L, Steltz SK, Luoto PK, Wolfe RR, Wong WW, Ludwig DS. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. Br Med J, 2018;363:k4583.

29. Nordmann AJ, Nordmann A, Briel M, Keller U, Yancy WS Jr, Brehm BJ, Bucher HC. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med, 2006;166(3):285-93.

30. Schoenfeld BJ, Aragon AA, Wilborn CD, Krieger JW, Sonmez GT. Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr, 2014;11(1):54. Published 2014 Nov 18. doi:10.1186/s12970-014-0054-7

31. R M Edinburgh, H E Bradley, N-F Abdullah, S L Robinson, O J Chrzanowski-Smith, J-P Walhin, S Joanisse, K N Manolopoulos, A Philp, A Hengist, A Chabowski, FM Brodsky, F Koumanov, J A Betts, D Thompson, G A Wallis, JT Gonzalez. Lipid metabolism links nutrient-exercise timing to insulin sensitivity in men classified as overweight or obese. The Journal of Clinical Endocrinology & Metabolism, October 19, 2019, dgz104, https://doi.org/10.1210/clinem/dgz104

32. Skip Breakfast Before the Gym by Gretchen Reynolds. NY Times. December 3, 2019

33. Gillen JB, Percival ME, Ludzki A, Tarnopolsky MA, Gibala MJ. Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women. Obesity (Silver Spring) 2013;21(11):2249-2255. doi: 10.1002/oby.20379

34. Horowitz JF, Mora-Rodriguez R, Byerley LO, Coyle EF. Lipolytic suppression following carbohydrate ingestion limits fat oxidation during exercise. Am J Physiol, 1997;273(4 Pt 1):E768-E775

35. Paoli A, Marcolin G, Zonin F, Neri M, Sivieri A, Pacelli QF. Exercising fasting or fed to enhance fat loss? Influence of food intake on respiratory ratio and excess postexercise oxygen consumption after a bout of endurance training. Int J Sport Nutr Exerc Metab, 2011;21(1):48-54