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How lean should you be? (“So you want to lose weight and look good naked?”)

  • Written by Gavin Guard

Key Takeaways

• Improving body composition is a main priority for improving overall health

• Just 5-10% weight loss can reverse prediabetes and diabetes

• But, achieving year-round six-pack status may come at a notable health risk

• A healthy body fat percentage is about 17-18% body fat in men, and low 30% in women- this is attainable for most with a good nutrition plan and regular resistance training

• In order to promote long-term health, maximize the amount of calories you eat while building muscle

So you want to lose weight and look good naked?

You are scrolling across Instagram and you come across a famous fitness “influencer”. They are posed in perfect lighting, minimal clothing, and have six-pack abs. You can’t help but think to yourself, “I want to look like that...”

Is this look even healthy?

In 2021, our perspective of health has become grossly distorted. Unfortunately, this has led many people to pursue goals that may be unattainable or at least, very difficult to achieve.

The good news is that a healthy body weight and body fat percentage is very achievable by most people. However, it’s important to consider a few key points if you wish to lose weight and look better naked.

That’s what we will uncover in this article.

Improving body composition is a main priority for improving overall health

If your desire is to lose some fat while gaining muscle, then your goal aligns with what it takes to maintain optimal health throughout the lifespan.

Unfortunately though, being a healthy weight is the exception, not the norm. An astonishing 91% of adults are overweight (1). Perhaps the most saddening fact is that over ⅔ (69%) of children are also overweight.

If we want to change the future trajectory of the health of our country, we need to focus on younger generations. However, we can only do this by leading by example- the change needs to start with us.

You’re in luck because weight loss is the main means to improve metabolic health. That’s right- special butter coffee, fancy supplements, and special diets are NOT the answer. In other words, you cannot biohack your way to better health. This means that optimal health is possible to the average middle-class American.

In a study of 150 diabetics, of those who maintained 20 pound weight loss at a 2-year follow up, about ⅔ achieved remission of their diabetes (2). This was despite these individuals needing about 50% less diabetes medications. It’s a win-win scenario- less disease with less medication.

5-10% weight loss can reverse prediabetes and diabetes

Similar to the study noted above, multiple other studies suggest that just 5-10% weight loss can reverse prediabetes and put diabetes into remission (3)-5). For example, losing 10-20 pounds for a 200 pound individual can result in dramatically improved metabolic health.

This is encouraging information as this degree of weight loss is extremely achievable with diet and lifestyle measures (3) (4) (5). A large study of 5,000 diabetics was conducted over a course of 8 years - this was a huge undertaking. They found that up to 50% maintained at least 5% weight loss and 27% maintained 10% weight loss. In other words, long-term weight loss is absolutely POSSIBLE.

Another study suggested that lifestyle changes that result in 5% weight loss can reduce the rate of diabetes by 90% at 3 year followup (3). Some studies show equal efficacy as compared to the common diabetic medication, Metformin.

A healthy body fat percentage is about 17-18% body fat in men, and low 30% in women- this is attainable for most with a good nutrition plan and regular resistance training

So what is a healthy weight? Perhaps, a better way to think about this question is to instead look at body fat percentage. This is simply the percentage of body weight that comes from fat tissue.

If we look at ancestral hunter-gatherer societies such as the Hadza tribe in Tanzania, the average body fat percentage is 9-18% for men and 21-28% for women (6) (7). Other studies suggest similar but somewhat higher body fat set points (8).

If we are to use this data and studies from what targets are associated with optimal metabolic health, a good goal is under 17-18% body fat for men and low 30% in women.

If you are over these thresholds, it’s worth it to get a comprehensive metabolic assessment that includes blood sugar management, inflammation, and cholesterol numbers. This is something I do for almost every patient in my clinic.

But, achieving year-round six-pack status may come at a notable health risk

Is there such a thing as being too lean? And similarly, are the fitness models you see in magazines and online also a model for optimal health? The long-story short is NO!

Living in a state of chronic calorie deficiency can actually be harmful.

Some studies have looked at what happens when individuals don’t eat enough. Something called “energy availability” describes the amount of calories available to your body after you take into account the calories you burn in exercise.

Below 13.6 Calories/pound of fat free mass can put you at risk for osteoporosis, sex hormone disruption, menstrual irregularity even in the short-term (5 days) (9). So for a 180 pound female at 35% body fat (117 pounds of fat free mass), she should be looking at eating at least 1,600 calories. And if that individual is burning 200 Cals/day through exercise, that jumps to 1,800 Calories. Yes, that’s right, 1,800 Calories. This is in stark contrast to the common 1,000-1,200 calories you see in many popular diet prescriptions.

Another big risk of getting too lean is losing muscle as you lose weight. Muscle mass loss is already common. Low muscle mass is found in almost 50% of overweight individuals, and increases diabetes risk by 40% (10) (11). In addition, muscle mass tends to decrease by about 0.5-1% per year after the age of 50, which equals 10% over the course of a decade (12).

You take this frequency of age-related muscle mass loss and compound that with weight-loss induced muscle mass loss, and you have a recipe for disaster. Without exercise, dieting can result in up to 46% of the lost weight coming from muscle mass (13) (14). The amount of weight loss coming from muscle mass loss can jump to 60-80% if you aren’t getting enough protein, not engaged in resistance training, sleep-deprived, or stressed out (15) (16).

So why is muscle mass loss such a big deal? Those with low muscle mass had a 150% increased risk of all-cause mortality (death) than those with preserved muscle mass (17) (18). Less muscle mass, strength, and power is predictive of fracture risk, falls, and disability (17) (19) (20) (21) (22) (10). Furthermore, more muscle mass is associated with better QUALITY OF LIFE (18).

All of this to say that muscle is important and preservation of muscle mass and bone health needs to be prioritized if you wish to diet and lose weight. It may be UNETHICAL to diet without doing some form of resistance training.

In order to maintain muscle mass while you diet to your goal body fat percentage, you’ll want to perform some resistance training and get enough protein throughout the day (14) (23).

In order to promote long-term health, maximize the amount of calories you eat while building muscle

So now you are at your body fat percentage goals that we discussed earlier. Now what?

Now is the time to maximize the amount of food you can eat while maintaining your new weight and body fat composition.

The fact is that you cannot diet forever. Because we live in an environment that is very prone to obesity (e.g. donuts and cookies are EVERYWHERE), we need to attempt to maximize the amount of calories we eat while maintaining weight.

One study suggests eating an energy availability goal of 20.5 Cals/pound of fat free mass (9). So taking that same 180# women at 35% body fat and burning 200 Calories per day, her new goal would be 2,600 Calories.

So how do you get to a point where you can eat MORE and not gain weight back on? The essentials come down to building enough muscle mass, performing resistance training, getting enough of protein, and not being sedentary.

One of the main strategies at our disposal is getting enough muscle mass on your frame. We can use a cool tool called a fat-free mass index (FFMI) calculator to see what our goal would be. This is essentially a number used to measure the amount of muscle mass you have according to your height and body fat percentage. It’s a much better predictor for metabolic health than BMI (24) (25). A goal FFMI for men would be at least 17 and ideally, 19-20. Whereas for women, it would be at least 14, and ideally 16-17. If you reach these numbers then you are considered “above average”.

To achieve this amount of muscle mass to maintain health, you'll need to get into a quality resistance training routine 2-3 times per week, eat enough protein, and not get stuck into being sedentary by walking at least 7-8,000 steps per day (14) (26) (10). This may sound daunting but if you take a long-term approach and build these steps into your routine over time, then you will be set for success for years to come.

Not only will muscle mass help you eat more in an environment of cookies and donuts, but you’ll also improve your metabolic health such as cholesterol levels and blood sugar balance (27). Resources Cite

All in all, muscle is good and there’s no such thing as too much, as long as you maintain a healthy body fat percentage.

The Bottom Line

A healthy body fat percentage looks to be under 18% for men and low 30% for women. You’ll want to get there with strategic habit changes that includes a resistance training program, adequate protein, and getting enough steps in throughout the day so that you don’t lose muscle while you diet.

After you get to your body fat percentage, try to maximize the amount of calories you eat while maintaining this new weight. You’ll also want to build enough muscle mass to protect you from the detrimental health impacts muscle loss has on your health, looks, and overall well-being.

Consider working with me to design a personalized plan to help you navigate your most frustrating health concerns.

I hope you found this information useful and helpful in your journey back to a healthier and happier life.

Like what you are reading? Learn more about how to take control of your health by signing up for the "5 Minute Health Makeover" where I coach you through 3 pivotal strategies for better health.

Resources Cited


1. Maffetone PB, Laursen PB. The prevalence of overfat adults and children in the US. Front Public Health. 2017 Nov 1;5:290.

2. Lean MEJ, Leslie WS, Barnes AC, Brosnahan N, Thom G, McCombie L, et al. Durability of a primary care-led weight-management intervention for remission of type 2 diabetes: 2-year results of the DiRECT open-label, cluster-randomised trial. Lancet Diabetes Endocrinol. 2019 May;7(5):344–55.

3. Uusitupa M, Khan TA, Viguiliouk E, Kahleova H, Rivellese AA, Hermansen K, et al. Prevention of Type 2 Diabetes by Lifestyle Changes: A Systematic Review and Meta-Analysis. Nutrients. 2019 Nov 1;11(11).

4. Pi-Sunyer X. The look AHEAD trial: A review and discussion of its outcomes. Curr Nutr Rep. 2014 Dec;3(4):387–91.

5. Pownall HJ, Bray GA, Wagenknecht LE, Walkup MP, Heshka S, Hubbard VS, et al. Changes in body composition over 8 years in a randomized trial of a lifestyle intervention: the look AHEAD study. Obesity (Silver Spring). 2015 Mar;23(3):565–72.

6. Pontzer H, Raichlen DA, Wood BM, Mabulla AZP, Racette SB, Marlowe FW. Hunter-gatherer energetics and human obesity. PLoS ONE. 2012 Jul 25;7(7):1–8.

7. Pontzer H, Wood BM, Raichlen DA. Hunter-gatherers as models in public health. Obes Rev. 2018 Dec;19 Suppl 1:24–35.

8. Kyle UG, Schutz Y, Dupertuis YM, Pichard C. Body composition interpretation. Contributions of the fat-free mass index and the body fat mass index. Nutrition. 2003 Aug;19(7–8):597–604.

9. Mountjoy M, Sundgot-Borgen JK, Burke LM, Ackerman KE, Blauwet C, Constantini N, et al. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med. 2018 Jun;52(11):687–97.

10. Mitchell WK, Williams J, Atherton P, Larvin M, Lund J, Narici M. Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front Physiol. 2012 Jul 11;3:260.

11. Khadra D, Itani L, Tannir H, Kreidieh D, El Masri D, El Ghoch M. Association between sarcopenic obesity and higher risk of type 2 diabetes in adults: A systematic review and meta-analysis. World J Diabetes. 2019 May 15;10(5):311–23.

12. Long DE, Peck BD, Martz JL, Tuggle SC, Bush HM, McGwin G, et al. Metformin to Augment Strength Training Effective Response in Seniors (MASTERS): study protocol for a randomized controlled trial. Trials. 2017 Apr 26;18(1):192.

13. Ardavani A, Aziz H, Smith K, Atherton PJ, Phillips BE, Idris I. The Effects of Very Low Energy Diets and Low Energy Diets with Exercise Training on Skeletal Muscle Mass: A Narrative Review. Adv Ther. 2021 Jan;38(1):149–63.

14. Cava E, Yeat NC, Mittendorfer B. Preserving Healthy Muscle during Weight Loss. Adv Nutr. 2017 May 15;8(3):511–9.

15. Wang X, Sparks JR, Bowyer KP, Youngstedt SD. Influence of sleep restriction on weight loss outcomes associated with caloric restriction. Sleep. 2018 May 1;41(5).

16. Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010 Oct 5;153(7):435–41

17. Abramowitz MK, Hall CB, Amodu A, Sharma D, Androga L, Hawkins M. Muscle mass, BMI, and mortality among adults in the United States: A population-based cohort study. PLoS ONE. 2018 Apr 11;13(4):e0194697.

18. Zhang X, Zhang Q, Feng L-J, Zhang K-P, Tang M, Song M-M, et al. The Application of Fat-Free Mass Index for Survival Prediction in Cancer Patients With Normal and High Body Mass Index. Front Nutr. 2021 Aug 4;8:714051.

19. Alajlouni D, Bliuc D, Tran T, Eisman JA, Nguyen TV, Center JR. Decline in muscle strength and performance predicts fracture risk in elderly women and men. J Clin Endocrinol Metab. 2020 Sep 1;105(9).

20. Uusi-Rasi K, Karinkanta S, Tokola K, Kannus P, Sievänen H. Bone Mass and Strength and Fall-Related Fractures in Older Age. J Osteoporos. 2019 Sep 9;2019:5134690.

21. Trombetti A, Reid KF, Hars M, Herrmann FR, Pasha E, Phillips EM, et al. Age-associated declines in muscle mass, strength, power, and physical performance: impact on fear of falling and quality of life. Osteoporos Int. 2016 Feb;27(2):463–71.

22. Marcus R. Relationship of age-related decreases in muscle mass and strength to skeletal status. J Gerontol A Biol Sci Med Sci. 1995 Nov;50 Spec No:86–7.

23. Strandberg E, Edholm P, Ponsot E, Wåhlin-Larsson B, Hellmén E, Nilsson A, et al. Influence of combined resistance training and healthy diet on muscle mass in healthy elderly women: a randomized controlled trial. J Appl Physiol. 2015 Oct 15;119(8):918–25.

24. Escobedo-de la Peña J, Ramírez-Hernández JA, Fernández-Ramos MT, González-Figueroa E, Champagne B. Body Fat Percentage Rather than Body Mass Index Related to the High Occurrence of Type 2 Diabetes. Arch Med Res. 2020 Aug;51(6):564–71.

25. Piqueras P, Ballester A, Durá-Gil JV, Martinez-Hervas S, Redón J, Real JT. Anthropometric indicators as a tool for diagnosis of obesity and other health risk factors: A literature review. Front Psychol. 2021 Jul 9;12:631179.

26. Wu T, Gao X, Chen M, van Dam RM. Long-term effectiveness of diet-plus-exercise interventions vs. diet-only interventions for weight loss: a meta-analysis. Obes Rev. 2009 May;10(3):313–23.

27. Savikj M, Zierath JR. Train like an athlete: applying exercise interventions to manage type 2 diabetes. Diabetologia. 2020 Aug;63(8):1491–9.

Most people feel frustrated because their health feels left to guesswork. I create a comprehensive and personalized plan that gives you answers to your symptoms.  After you work with me, you will feel more in control of your health.
I am now offering a free 15-minute appointment to help you develop a game plan for your health concerns. Go to www.GavinGuard.com to book this free appointment.

In Health,

Gavin Guard, PA-C, MPAS, CISSN, Pn1
Medical Director, Roots Integrated Care