How Low Can You Go In Body Fat Levels While Staying Healthy


Nope, this is not an article on how to limbo to lose fat. It is a fact-chasing pursuit of how low a person’s body fat can get before the body goes into crisis mode and starts tearing down muscle to fuel the metabolic needs of survival.

SkinnyGuySurvival makes it sound like some cable channel show of a hairy guy with questionable hygiene showing which bugs can be eaten when one has somehow ended up in middle of a frozen tundra or Central American rain forest. The body doesn’t use maps, it goes off of environmental cues that you provide – what temperature is the house set at; how much/little sleep are you getting; how much and what type of food are you eating; are you in hostile or supportive relationships; etc.

Fat loss – you eat less and exercise more. Some people do it by choice, joining a gym and hiring a trainer; others are in situations due to employment (military deployment) or unemployment (no car, less money for groceries). Looking at the group who is actively seeking fat loss, there is an universal experience that happens for those who succeed initially – the plateau. It sucks. You do well, feel good, and are rewarded emotionally and socially. Then, nothing. The scale won’t move (or won’t move in the right direction), you get weaker and less motivated despite being more desperate, and ugly things happen to your skin, hair, joints, etc.

There are several causes for this, and typically people think of the obese person who loses fifteen or twenty pounds and stops. The body doesn’t like changes in body mass of more than 10%, especially if you have previously been at that weight for months or years. Your cells, hormones, and systems don’t look in the mirror; they look for change. Sudden or prolonged change to the amount of glucose, leptin, melatonin, etc, and your regulatory systems want to go back to what was warm, cozy, and familiar. This is a conserved programming that developed over many, many generations of humans who suffered famine, extremes in weather, war, and other challenges. Remember, it is only within the last hundred years or so that automobiles, refrigeration, and other industrial advances made it possible to live in relative comfort with reliable food supply. The U.S. had food rationing as recently as World War II.

Watch some shows from the 1960s and 1970s, not the remakes which generally are not near as good with the exception of Battlestar Galactica. Aside from the big hair and bell bottom jeans, one feature that stands out is the near absence of obese people. It is not just Hollywood putting “beautiful” people on the screen back then either. Obesity and overweight were not an issue until the last couple of decades. People try to pin the change on fructose, sedentary jobs, total calorie consumption, endocrine disruptors, etc. The fact is that the causes are multi-factorial, but the end result is clear. American society has become overweight and obese. For those starting from a relatively high body mass/body fat, plan for periods of frustration after you lose about 10% of your body mass. However, stay there and eventually your body will let you drop some more. Modern medicine’s latest solution is gastric bypass surgery, but hopefully, many of you who are affected by obesity will attempt lifestyle changes first.

Greedy man eating burgerWhat about the average weight person with “normal” body fat who wants to get lean? Yes, there are a lot of rewards to having a “six-pack” and a V-taper. However, make sure that your goals and efforts are mentally healthy. Some people get fixated on their bodies, or have such extreme weight loss goals that they harm self and their relationships with others. Eating disorders or “body dysmorphia” are not benign conditions.

So, all that said, healthy average person wants to get as lean as healthily possible. What is that point? Well, first, why is this important? A lot of people think they are “healthy” because their weight puts their BMI (body mass index) in the “normal” category. Unfortunately, the BMI was created for convenience. There are two better indications of “fat” health – waist circumference and body fat percentage. Dealing with waist circumference in the simplest fashion, men are at risk of metabolic disease states (e.g. type 2 diabetes, hypertension, cardiovascular disease, etc) when the waist measures over 40″ and for women the limit is 36″. It doesn’t matter if you are “normal” or just “overweight” by BMI when your abdomen exceeds these points due to a number of physiologic changes that can get complicated. So, regardless of your weight, check your waist. If it is over those limits (40″ for men, 36″ for women), get to work. See your doctor, seriously, to see if you have high blood pressure, high fasting blood glucose, elevated cholesterol and triglycerides, changes in liver and kidney function. Why die when you can try?

The more applicable measure for that group I keep bringing up and getting distracted from (normal weight with average body fat) is body fat percentage. Now, before I get into numbers, let me make clear one thing – NEVER USE BIOELECTRIC IMPEDANCE! You know, those scales with the silver sensors that measure your body fat by electrical resistance. I don’t care if it is so handheld device guaranteed by a health club trainer to be accurate. They are not. In fact, sometimes they are so far off it is not only laughable but can discourage people from continuing to try.

It is not practical to suggest underwater weighing, Bodpod testing, or DEXA scans. They are accurate but also expensive and not readily accessible. What then? Calipers. Those pinchy things that go on the most ticklish spots of your body that require you to lift your shirt in front of some stranger so he/she can apply these devices repeatedly in the hopes of assessing your fatness. Calipers have some inaccuracy as well, and part is due to operator error. This means the person holding the calipers needs to know where to apply them and how to grab your skin to get an accurate reading. It means they need to take three measures and average them, plug them into the correct formula and follow the tables. There are a lot of places that use a computer program, and that is fine as it allows for tracking over time without depending upon you to write down the numbers every time.

Personal trainer measuring shirtless muscular client's body fatNow, the calipers can use a number of different sites in different combinations, and researchers are still playing around trying to find the most accurate. It is a matter of degree, and frankly, calipers (also called skinfold testing) are close enough. The true value to the individual being measured is following progress. So, every couple weeks you go in and you can see if you have lost as little as one millimeter on any of up to six skinfold sites.

The numbers go into a formula, and which formula it is depends upon which and how many sites were tested. That generates a raw body fat percentage, as well as the person’s gender since boys are different from girls. That number is then adjusted to account for the person’s age group. The average person accumulates fat in different places as he/she ages. Subcutaneous fat is what is measured using the calipers, but older people develop fat in the bone marrow, inside organs, within the abdominal cavity, and between the ears based upon some people’s behavior. OK, the between the ears option doesn’t really happen, much. This is why measurements on a 20 year old will generate a body fat that is lower than the same values on a 55 year old. Of course, many 20 year olds are not as healthy anymore, and there are a lot of Baby Boomers and Generation X individuals who are in incredible shape. So, the formulas can deviate from being accurate the less “normal” you are compared to your age group peers.

Lean and muscularPersonally, I just use the unadjusted body fat, but my waist is 32″ and I have been active for the vast majority of my adult life. Using my experience as an example, mostly because I know the numbers, I have been as low as in the 3% range during my drug-free bodybuilding days (though very depleted and dehydrated on that testing, so it was not entirely accurate), was measured at 4.4% uncorrected and 8.8% corrected a couple years ago before my back and shoulder surgeries, and now am closer to 8% uncorrected. I hope to get back down to around 6%, but Thanksgiving is coming up.

Let me say a couple things about my measures. I don’t think I was in the 3% range when I was tested prior to a competition in the late 1990s. I was dehydrated, and that affects subcutaneous thickness. The measures should be taken at rest, in a hydrated state. The time I was measured at 4.4%, it was after a workout and though I was hydrated, I was also pumped. Why didn’t I get a later measure to obtain a valid result? Hey, I am human and it was very rewarding to see those numbers. Frankly, the difference likely resulted in the numbers being low by 1% +/_.

So, in truth, I was probably just under 6% in valid testing conditions when I was not competing a couple years ago. My competition body fat was likely in the 4% range, but I was physically weak and had lost muscle mass to get there too. My goal that year was to come in shredded, which I did. I placed 10th in the Musclemania World Championships in my weight class, against a huge class from around the world. IFBB pro Jose Raymond who placed third in the lightweight category of the Mr. Olympia this year placed fifth in my weight class during the 1998 Musclemania.

Assuming I do everything right (I’ll pause until you stop laughing), where do my results stand according to the literature? Am I leaving something on the table? Am I pushing it too hard and sacrificing lean mass gains or affecting my health? Well, for some time I thought I was leaving something on the table, meaning I could try harder, or follow a better program or diet. This lead me to periods where I would overtrain and/or lose hard-earned gains by trying to get leaner than my body would allow. In fact, to preserve my life (in the eyes of my sightless organs and glands), it was better to tear down muscle or make me fatigued than allow the loss of any more fat.

Two articles have recently caught my attention, as they provide guidance in terms of what is a proper goal for the lower limit of body fat. Let me apologize to the ladies, the research followed male subjects, so the remainder of specifics is for them. However, I will try to offer some insight for women at the conclusion.

The first article was published in 1985 and followed 55 men during an Army combat leadership course that lasted eight weeks. These men were all physically active and healthy prior to entering the course. The course involved significant physical stress, limited sleep and hypocaloric diet. On average, the men lost 15% of their body mass. That would be 30 pounds for a 200 pound person. During this time, the average body fat dropped from over 14% to 5.8%, with some getting into the 4% body fat range. Some men dropped into the 4 – 6% body fat range early during the course, within the first six weeks. However, from that point on, skin folds stayed constant and the remainder of weight loss came from lean mass (muscle). The researchers did note that the skinfolds reflected upper body sites, and that the hips, thighs, and pelvic girth measures continued to drop in the men who reached low body fat percentages. Thus, there was some continued fat loss, though it came from sites traditionally resistance to loss. Further, the authors of that study noted the final results were very similar to a study performed during the 1950s in which people were subjected to a 25% weight loss. The end body fat percentage for that group was 5.2%, essentially the same. The conclusion was that the minimal amount of body fat needed – yes, NEEDED, for health is about 1 kg per meter squared. I know, metrics and algebra in one sentence. The lower limit for body fat is 4 – 6%, and around 2.5 kg or roughly 5 pounds. So, those of you going for absolute zero, stop it. You are being as foolish as I was, and that is really foolish.

MaleBodyTypesThe second study is more recent, published in 2010. It followed contestants in a Mr. Fitness event taking place in Oman, a country in the Middle East. The researchers followed a lot of measurements, and the results were not surprising, bearing in mind it was a “Fitness-physique” being sought as opposed to the greater mass associated with bodybuilding. The end result, based upon a number of criteria, the opitimum body fat was 5.6 – 6.7%.

Both groups, the soldiers and the “Mr. Fitness” contestants were drug-free, demonstrating the possible lower threshold for body fat without entering a state of catabolism. Even within that range, continued exposure to excessive physical stress or insufficient nutrition resulted in the loss of lean mass rather than aesthetic or healthy loss of additional body fat.

So, for all you men sitting at or near 6% body fat, congratulations, you have arrived. Push it any further and you will likely lose strength, lean mass, and be more susceptible to getting sick.

Ladies, there are a lot more issues to consider, and as seen from the military group of men, lower body fat is more resistant to loss. Based upon measures of endurance athletes, and elite gymnasts, about 9% is the lowest that is achieved without serious performance loss. However, at that level, changes in menstrual pattern occur and rate of injury increases. It should also be noted that the conditions to achieve that degree of “leanness” required training and calorie restriction that would be considered abusive in many settings. A study published this year looked at the measures of athletes in a variety of sports, and the general values for female body fat were in the high teens to mid twenties for body fat percentage. Again, presumably this was a drug free group involved in organized sport.

10407588_806536552721164_7370927185569471927_nFrankly, what is attractive is often consistent with what is healthy. My wife and I watched “Pumping Iron” last night on Netflix. It is amazing to see the bodies that created the phenomenon that is bodybuilding from the vantage point of forty years later. Arnold, Lou Ferrigno, and many other greats were present in the film. It is impossible to guess at this point, but I would venture to say that Arnold’s body fat in the 1975 Mr. Olympia was no lower than 5%. And he looked great. Sure, he would not qualify for an upper level amateur show in that condition now, but is the look better? Are the bodybuilders healthier? Is the sport healthier? It could be challenged that the sport has pushed the contestants beyond the point of physiologic tolerance, which is also less attractive to the general public. It is hard to say where bodybuilding will be in another forty years, but given the emergence of the physique/fitness/boy-toy contests, it is clear that the public’s interest is deviating.

Male Pinching Fat From his WaistMany people criticize bodybuilding for not clamping down on the extremes, but more importantly, who is “clamping down” on the fitness enthusiast or gym rat who is privately attempting to achieve a drastic level of muscularity or leanness? Hopefully, learning of these studies will provide you with some guidance as to what a realistic goal is, as far as dropping body fat. If your desire is to get “peeled” to the point that every muscle fascicle is exposed under your compression shirts, your final destination may be as a medical cadaver. Then your body fat gets down to near-zero.

Don’t kill yourself, and unless you have a short-term goal (such as a bodybuilding contest), a body fat in the 5 – 6% range is as good as a FICO credit score over 800. Few people achieve it and everybody respects it.

_DSAbout the Author

Daniel Gwartney, M.D. took the path less traveled and combined his passion for health, fitness, and bodybuilding with the knowledge and experience learned during his medical training. A former world-ranked natural bodybuilder, appearing on the covers of Muscle Media 2000 and Ironman Magazine, and a regular contributor to several of the top bodybuilding and fitness magazines, he provides unique insight into the application of fitness into medicine and medicine into fitness.


Friedl KE, Moore RJ, et al. Lower limit of body fat in healthy active men. J Appl Physiol (1985). 1994 Aug;77(2):933-40.

Kilani H, Abu-Eisheh A. Optimum anthropometric criteria for ideal body composition related fitness. Sultan Qaboos Univ Med J. 2010 Apr;10(1):74-9.

Santos DA, Dawson JA, et al. Reference values for body composition and anthropometric measurements in athletes. PLoS One. 2014 May 15;9(5):e97846.