• The best way to lose fat without losing muscle is a combination of high protein and resistance exercise.
  • Dieting individuals need a higher ratio of EAAs to stimulate muscle protein synthesis than when not dieting.
  • Resistance exercise preserves lean mass losses, whereas cardio will not.
  • Weekly weight losses between 0.5-1% have been suggested as optimal; however, this depends on the amount of body fat starting the diet to determine the appropriate deficit.


Low energy intake/low calories have long been known to disrupt endocrine, metabolic, and physiological dysregulation, resulting in the loss of lean muscle. The Female Athlete Triad and RelativeEnergy Deficiency in Sport (RED-S) syndromes describe the effects of chronic low energy availability on health and performance outcomes.

Total calories dictate the metabolic consequences of weight loss. In conjunction with resistance exercise, high-protein diets can prevent the loss of lean muscle, but if the caloric restriction is too low, not even high protein will not completely prevent muscle loss.

Large caloric deficits in conjunction with rapid rates of weight loss (>1 kg/per week or 2.2 pounds per week), which would require a caloric deficit of ~1,000 calories per day, are associated with a greater propensity for lean mass loss and potential declines in performance.(7)


In a study of male combat sports athletes, keeping calories at 20 kcal/kg/fat-free mass per day with a high protein diet was sufficient to reduce body fat and body weight without reductions in testosterone hormone levels or losses in lean muscle mass. However, when the athletes dropped calories to <10 kcal/kg/fat-free mass, they experienced reductions in decreased testosterone and losses in muscle.(8)


The best example of adequate calories being inadequate comes from studies of soldiers undergoing combat training simulations. They can be provided with high-protein diets and perform vigorous exercise, but they will lose weight and lose muscle mass if the calorie deficit is too low. Soldiers consumed 5 kcal/kg/fat-free mass during intense combat training.

High protein supplementation after severe caloric restriction did not enhance the restoration of lean mass above those eating ~ 2 g/kg/bw. (i.e., 1.1 grams of protein per pound of body weight)(9) It has also been found that prolonged calorie deficits <25 kcal/kg/FFM is the threshold for bodybuilders while dieting to prevent muscle loss.(10)

Dr. Helms, in his book the Muscle and Strength Pyramid: Nutrition, recommends that women should try and stay above 30 kcal/kg/LBM (~13.6 kcal per pound of lean mass) and men stay ~25 kcal/kg/LBM (~11.4 kcal/lb/LBM).(11)

biceps, triceps, fit
High protein supplementation after severe caloric restriction did not enhance the restoration of lean mass above those eating ~ 2 g/kg/bw. (i.e., 1.1 grams of protein per pound of body weight)(9)


Low energy availability can also result in a reduction in testosterone. Many factors can influence hormone levels, and dietary fat and testosterone are connected to lean mass. Low energy availability has decreased both luteinizing hormone (i.e., a hormone produced in the brain that signals the testes to produce testosterone) and testosterone.

For example, study participants were categorized as having low energy availability (<30 kcal/kg/FFM/day) and had significantly lower testosterone levels than those that were classified as a moderate energy availability (30-45 kcal/kg/FFM/day).(12)

A high testosterone diet plan needs adequate calories for normal testosterone functioning. A testosterone meal plan should raise calories back to slightly higher maintenance levels after dieting. There is some truth to the eggs & steak testosterone boosting effect, which can be attributed to the rich source of protein, fats, and calories. Fear not. Low-carb diet and testosterone levels can be maintained for those on low-carb diets.

LOSE FAT WITHOUT LOSING MUSCLE: The Importance of High Protein

The higher the protein intake, the lower the chance of lean muscle loss. However, if the caloric deficit is large enough, high protein will only partially prevent losses of lean muscle mass. Resistance exercise is the key to maintaining lean muscle mass while dieting. A six-week high protein diet alone (2.8 g/kg/bw or 1.3 grams per pound of bodyweight) was not able to prevent lean muscle loss during a moderately calorie-restricted diet.

Lean mass accounted for 47% of the weight loss. (13) In a study of rowers, a 6% body weight loss over 8 weeks resulted in 50% of their lean mass. The authors suggested that the very low body fat of the athletes starting the diet rapidly accelerated lean muscle losses.

Thus, if calorie restriction is severe enough and the initial body fat is low, even exercise will only partially prevent lean muscle loss.(14) It has been found that a moderate energy restriction of .7-1.4% absolute body weight loss per week can retain lean muscle mass.

When subjects underwent a 40% restriction in calories for ten days, despite consuming 2.4g/kg/bw or 1.09 grams per pound of body weight, they still lost lean mass and reduced protein synthesis.(15) In another study, despite subjects consuming 35% of their calories from protein, when subjects consumed a liquid low-calorie diet (<800 calories per day), they still lost muscle.(16)


Studies in athletes have found that during periods of intense exercise and consuming 2 g/kg/bw (close to 1 gram per pound of bw), being in a slight caloric restriction, athletes still had negative nitrogen balance (i.e., breaking down more protein than building).(17)

Pasiakos et al. examined three different levels of protein (0.8 g/kg.bw (RDA), 1.6 g/kg/bw (2X the RDA), and 2.4 g/kg/bw(3 X the RDA). The subjects were placed in a 40% caloric deficit, with 30% from dietary restriction and 10% from exercise.

The portion of lean mass loss was lower, and fat loss was higher in subjects consuming 2X and 3X the RDA compared to the lower protein RDA. There were no differences in the losses in lean mass between the 2X and 3X higher protein groups, but they still lost some lean muscle.

The ratio of lean mass loss to fat mass loss was the following: RDA for protein (58:42), 2X RDA (30:70), and 3x RDA (36:64). The proportion of weight loss due to reductions in fat mass and lean mass was not different between 2X RDA and 3X RDA.(18, 19) If exercise levels are high (i.e., burning 1000 calories per day), increased physical activity results in a decline in the anabolic hormone IGF-I. These response patterns were not altered by dietary protein intake.(20)


Thus, severe caloric deficits (>40%) despite high protein can lead to losses in lean mass in various muscle groups. In contrast, moderate decreases in calorie restriction with exercise can completely preserve and/or increase lean mass.(21)

Studies in the military have provided some interesting aspects of severe caloric restriction on lean mass despite having protein supplementation. When a 40% caloric restriction was followed for 21 days, despite the soldiers receiving whey protein (25 grams) resulted in a blunted anabolic signaling response.

Another study found that four 20 g whey protein supplements per day failed to increase whole-body protein retention during a multi-day strenuous winter military training exercise that elicited a severe energy deficit (54% energy deficit).(22) Elite gymnasts who restricted their calories by 400 calories per day and consumed a high-protein diet were able to drop body weight and body fat while maintaining lean mass.(23)

best diet for testosterone, best testosterone diet, best diet to increase testosterone, best diet for high testosterone, best diet for increasing testosterone
Moderate decreases in calorie restriction with exercise can completely preserve and/or increase lean mass.


When an essential amino acid is missing from the diet, this results in a dampened protein synthesis response. An incomplete protein is missing at least one essential amino acid. If a diet lacks an essential amino acid (i.e., incomplete proteins), foods such as beans, specific nuts, and tofu will not give you all of the amino acids your body needs.

This is why some amino acids are called essential amino acids. Complete proteins contain all the essential amino acids. Amino acids are the building blocks of muscle.

The 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The best essential amino acid supplements should contain all 9 amino acids.


Certain amino acids are called essential amino acids because they are needed for optimal health. When an essential amino acid is lacking from the diet, sub-optimal increases in protein synthesis occur. Plant-based foods and plant-based diets are lower in BCAAs and EAAs compared to meat-based products on a gram-per-gram basis. The BCAAs include leucine, isoleucine, and valine.

Under the normal, non-caloric restriction, ingesting ~20 to 30 g protein or ~10g grams of an essential amino acid complex optimally increases muscle protein synthesis in healthy adults consuming habitual protein intakes of 1.6 g/kg/day during post-resistance exercise.(24) It may be advisable to increase your intake of EAAs through supplementation to preserve lean mass.

In contrast to whole-food proteins and protein supplements, EAAs are absorbed and enter peripheral circulation rapidly, resulting in robust increases in EAA concentrations. High doses of EAA’s supplementation (~24 grams) during a ~30% caloric restriction resulted in greater protein synthesis and less protein breakdown than a control drink of lower EAAs (~8 grams). It was suggested that higher EAAs are needed to offset the catabolic conditions of calorie restriction.(25)

10 grams seems to be the appropriate dose for stimulating muscle protein synthesis; however, larger dosages of EAAs can prevent muscle tissue breakdown when in a caloric deficit. Interestingly, the military is investigating the use of EAAs during soldier operations to prevent lean muscle loss. Since EAAs rather than protein are the drivers of anabolism, the military is looking to maximize protein synthesis with rations rather than focus on total protein.


  • To lose fat without losing muscle, one must increase protein intake and perform resistance exercise. 
  • Dieting individuals need a higher ratio of EAAs to stimulate muscle protein synthesis than when not dieting.
  •  Resistance exercise preserves lean mass losses, whereas cardio will not.
  •  Weekly body weight losses between 0.5-1% have been suggested as optimal; however, this depends on the amount of body fat starting the diet to determine the appropriate deficit.


1. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104.

2. Langan-Evans C, Germaine M, Artukovic M, Oxborough DL, Areta JL, Close GL, et al. The Psychological and Physiological Consequences of Low Energy Availability in a Male Combat Sport Athlete. Medicine & Science in Sports & Exercise. 2021;53(4):673-83.

3. Berryman CE, Sepowitz JJ, McClung HL, Lieberman HR, Farina EK, McClung JP, et al. Supplementing an energy adequate, higher protein diet with protein does not enhance fat-free mass restoration after short-term severe negative energy balance. Journal of Applied Physiology. 2017;122(6):1485-93.

4. Fagerberg P. Negative Consequences of Low Energy Availability in Natural Male Bodybuilding: A Review. Int J Sport Nutr Exerc Metab. 2018;28(4):385-402.

5. Eric Russell Helms AM, Andrea Marie Valdez The Muscle and Strength Pyramid: Nutrition. 2019.

6. Heikura IA, Uusitalo ALT, Stellingwerff T, Bergland D, Mero AA, Burke LM. Low Energy Availability Is Difficult to Assess but Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes. International Journal of Sport Nutrition and Exercise Metabolism. 2018;28(4):403-11.

7. Roth C, Rettenmaier L, Behringer M. High-Protein Energy-Restriction: Effects on Body Composition, Contractile Properties, Mood, and Sleep in Active Young College Students. Frontiers in Sports and Active Living. 2021;3.


8. Koutedakis Y, Pacy PJ, Quevedo RM, Millward DJ, Hesp R, Boreham C, et al. The effects of two different periods of weight-reduction on selected performance parameters in elite lightweight oarswomen. Int J Sports Med. 1994;15(8):472-7.

9. Hector AJ, McGlory C, Damas F, Mazara N, Baker SK, Phillips SM. Pronounced energy restriction with elevated protein intake results in no change in proteolysis and reductions in skeletal muscle protein synthesis that are mitigated by resistance exercise. The FASEB Journal. 2018;32(1):265-75.

10. Magkos F, Hjorth MF, Asping S, Rosenkrans MI, Rasmussen SI, Ritz C, et al. A protein-supplemented very-low-calorie diet does not mitigate reductions in lean mass and resting metabolic rate in subjects with overweight or obesity: A randomized controlled trial. Clin Nutr. 2021;40(12):5726-33.

11. Butterfield GE. Whole-body protein utilization in humans. Med Sci Sports Exerc. 1987;19(5 Suppl):S157-65.

12. Pasiakos SM, Cao JJ, Margolis LM, Sauter ER, Whigham LD, McClung JP, et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. The FASEB Journal. 2013;27(9):3837-47.

13. Villareal DT, Smith GI, Shah K, Mittendorfer B. Effect of Weight Loss on the Rate of Muscle Protein Synthesis During Fasted and Fed Conditions in Obese Older Adults. Obesity. 2012;20(9):1780-6.

14. Rarick KR, Pikosky MA, Grediagin A, Smith TJ, Glickman EL, Alemany JA, et al. Energy flux, more so than energy balance, protein intake, or fitness level, influences insulin-like growth factor-I system responses during 7 days of increased physical activity. J Appl Physiol (1985). 2007;103(5):1613-21.


15. Campbell WW, Haub MD, Wolfe RR, Ferrando AA, Sullivan DH, Apolzan JW, et al. Resistance Training Preserves Fat-free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women. Obesity. 2009;17(7):1332-9.

16. Margolis LM, Murphy NE, Martini S, Gundersen Y, Castellani JW, Karl JP, et al. Effects of Supplemental Energy on Protein Balance during 4-d Arctic Military Training. Med Sci Sports Exerc. 2016;48(8):1604-12.

17. Paoli A, Grimaldi K, D’Agostino D, Cenci L, Moro T, Bianco A, et al. Ketogenic diet does not affect strength performance in elite artistic gymnasts. Journal of the International Society of Sports Nutrition. 2012;9(1):34.

18. Gwin JA, Church DD, Wolfe RR, Ferrando AA, Pasiakos SM. Muscle Protein Synthesis and Whole-Body Protein Turnover Responses to Ingesting Essential Amino Acids, Intact Protein, and Protein-Containing Mixed Meals with Considerations for Energy Deficit. Nutrients. 2020;12(8):2457.

19. Gwin JA, Church DD, Hatch-Mcchesney A, Allen JT, Wilson MA, Varanoske AN, et al. Essential amino acid-enriched whey enhances post-exercise whole-body protein balance during energy deficit more than iso-nitrogenous whey or a mixed-macronutrient meal: a randomized, crossover study. Journal of the International Society of Sports Nutrition. 2021;18(1).

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