Downsides Of Having Too Low Body Fat Index

Today the fitness and nutrition world has advanced to a very large extent. There are countless super foods, diets, dietary supplements, fitness and training programs, exercises and concepts that are designed for different purposes, one of which (perhaps the most discussed and desired of them all) is losing excessive body fat and building lean muscle.

The extreme motivation of some individuals makes them engrossed in this to the point where they want to reach their full potential and become somebody with a “perfect physique”, with no fat and enviable brawn. However, such obsession could very easily become morbid, because as lean as possible may not always be better and healthier, in other words, very low body fat can be harmful, and it’s for your own sake to learn when enough is enough, to be optimally ripped and sustain that result it in time.

First off, let’s say that the average body fat % of men, according to Pennsylvania State University, is between 15% and 20%, from which 3% is critical as you would die without it. For adult women, average norm is considered somewhere between 25%-31%, and 14%-20% for athletes. Georgie Fear, R.D, the author of Lean Habits for Lifelong Weight Loss, a body fat percentage below 5 is thought to be a result of bad health even in professional athletes, even though some bodybuilders go below that limit for competitions. Basically, the most optimal % range for male athletes is 6%-12%, and if you’re a vocational athlete that’s what you should be aiming for, depending on your type of sport and goals. The following charts will give you some synthesized info about the average male and female body fat indexes, depending on the age group, and whether it is a professional athlete, a fitness fan, average person or an obese one we’re talking about.



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Before proceeding with the bad sides of having too small body fat percentages, let’s discuss how can one learn how much fat they have, because it’s always good to know as much about your body composition as possible, especially if you want to alter it.

How to measure your body fat percentage?

In case you want to follow your body fat norms more closely, there are several ways to do that.

1 – Just take a look

Well duh, it’s the simplest way if you can’t afford anything else for the time being. However, this method needs a practiced and sharp eye, plus it’s not exactly the most accurate. You can take a photo of your body, then for example after a month, you can try and make a comparison between the picture and your current look.

2 – Measurement method

By taking different measurement methods, such as the YMCA calculator or the US Navy Calculator, you can determine your body fat percentage without any specific tools. The only small flaw of these techniques are the deviations from the accurate body fat index, which is presumably expected, since all you provide for the calculator are a few points of data.

The YMCA calculator works with a special formula created by the YMCA. Use a tape measure and enter your waist proportions. Combine the waist measurement with your weight and gender, and the calculator will estimate your body fat. It will also give you information about what part of your body weight is lean muscle mass, and how much of it is fat mass. It will also point your general fitness category depending on the results. This test is usually accurate with small variability within 1-3%.

The US Navy calculator utilizes the U.S Navy fitness formula to assess the approximate body fat percentage. Get a tape measure then enter your waist, neck, and hip measurements. Combine them with your height and gender, and similar to the YMCA, the US Navy calculator will estimate your body fat percent, fat mass, lean mass and the basic navy fitness category. Again, accuracy deviations are 1-3%.

3 – Skin calipers a.k.a the skinfold measurement method


Skin calipers won’t cost you much, and are a quick way to gauge your body fat. They’re the most accessible (and perhaps that’s why a very common) means for the purpose, all it takes is a little pinch. Pull the fat away from your muscles with your fingers. Apply the caliper and take measurements. Take a look at the body fat charts above to determine your body fat percentage. Some experts recommend using 1 test site, others recommend using multiple. This method does the trick to some point, though some people report that measuring body fat with calipers tends to underrate body fat percentage a bit by showing your fat from 2% to 3% less than actual. Still, it’s pretty good for a cheap way to assess body fat.

4 – Bioelectrical impedance scales


This might sound scary, but it’s actually not, and when the test is run you don’t feel a thing. Bioelectrical impedance scales type ranges from simple, which is a normal scale with electrodes under both feet, to a complex one which is equipped with handholds with additional electrodes. Both types work by sending small electrical impulses through the body, and measure how fast those impulses return. Lean tissue conducts electrical currents faster than fat tissue, therefore a quicker impulse response is related to a leaner body and better shape.

This device does have its advantages, it’s small and affordable enough to have one in your house, it’s not complicated for usage since it requires nothing more than pressing a button, it’s found in many fitness gyms, plus results come out in seconds. The downside of this tech is again accuracy caused by a few factors. First, readings can be affected by your body hydration levels, because water is also a conductor of electrical impulses. Second, meal times can also screw with results. Third, workouts too can impede more precise readings, because if you take a test right after exercising, body fat percentages can be lower than actual.

If you want to own one of these body fat measurement devices, the Omron body composition monitor with scale seems like a good choice.

5 – Dual energy X-ray absorptiometry (DEXA)


It’s a surprise to some, but X-Rays aren’t just for showing whether you have a broken bone. A DEXA scan test exposes the body to X-ray beams with different intensities, and can be used for measuring body composition, as well as bone mineral density. All you have to do is lie on a table while the X-ray machine passes above through the whole body, emanating low and high-energy x rays. The technicians measure the absorption of each beam into different body parts. That’s how they receive readings regarding lean body mass, fat mass, and bone density. The machine scans each body part individually, therefore it can give detailed information about each limb’s composition. That’s how you can confirm for example that one of your legs/arms is stronger than the other.

The good thing about DEXA tests is that they’re exceptionally accurate at measuring your body composition. You won’t have to put any efforts in the procedure, as you only lie at the table for a few painless minutes.

The disadvantages? Well, this is somewhat some impressive tech, and such machines can’t exactly be found around the corner to be at your disposal. To undergo such a test, you must make an appointment at a specially equipped hospital with the concrete medical professional. Also, let’s not forget that such services don’t come that cheap. Another major disadvantage are the probable health-related issues many people have been talking about for years. After all, X-rays expose you to radiation which causes cell mutations that can result in cancer, especially if radiation amounts during numerous tests are considerable.

6 – Hydrostatic weighing

You like swimming and getting underwater? Then this method suites you! Also known as underwater weighing, it practically compares the participant’s regular body weight with their body weight when submerged. With these pieces of data and given the water density, those who conduct the test can see your body’s density, and this quantity can be used for determining the body composition with pretty high punctuality.

Accuracy is one of the perks when using this technique to check your body fat percentage and your entire corporal composition. The displayed variables usually have very minimal errors. With that in mind, hydrostatic weighing is often considered to be one of the best ways for assessing body composition.

The shortcomings of this method are again correlated with harder accessibility, since such complicated equipment won’t be found in every tech store, not even in every hospital. You’ll have to search a little to find a laboratory, performance center or an advanced medical center that possesses an underwater scale. Just like DEXA, underwater weighing comes at a rather high price tag, usually varying from 40$ to 60$, depending on the exact location. The other delicate detail is that you have to exhale as much air out of your lungs as possible before you go underwater, or else there would be higher chance for error. This might be uncomfortable for many people if they aren’t used to holding their breath when submerged underwater.

7 – Air displacement plethysmography

Don’t be frightened by the name. The air-displacement plethysmography is actually not so different than water scales. First, the subject enters a small machine capsule, such as the BOD POD, then by measuring how much air the participant displaces, operators can specify body density. After that density is used to calculate the body composition more circumstantially.

One of the pros of this method is that it doesn’t require you getting underwater, hold your breath for a while and so on and so forth, which means many people would consider it more comfortable. As we mentioned, the shape of the machine resembles an egg-like capsule with the size and space to accommodate a person of any age and weight.

What’s the bad thing about it? We bet you already have guessed that the main disadvantages of the air-displacement plethysmography are connected with unpleasant financial costs and limited accessibility. You will not find this high technology in every medical facility or lab, definitely not in the closest fitness gym, plus you’ll probably have to pay somewhere between 45$ and 60$ for each scan.

No matter which technique you choose to determine your body fat percentages, it would be best to resist the urge to take measurements every week, because results take time, and patience is definitely a virtue in this case.

With that being said, let’s keep in mind that healthy levels of body fat are needed for keeping your endocrine, cardiovascular, reproductive, skeletal, and central nervous system in check.

Many would wonder what’s so bad about having minimal fat percentage? There are more than couple of arguments that would convince you.

Downsides of having too low body fat index

1 – Energy levels go low

When you deprive yourself from too much fat, you don’t have energy reserves. Your body won’t be able to function properly, as it requires sufficient energy to do so. To boot, too low fat index is connected to thyroid dysfunction, and slow heart rate, according to Dr. Fear.

2 – You start to have nagging food cravings

When roasted fish, chicken breast and fresh veggies are your staples for some time, pizza, spaghetti, chips and chocolate start to occupy your mind more often than you’d like. When you’re dieting and you’re having low body adiposity, circulating levels of the hormone leptin start to decrease drastically. Your leptin receptors, located in the hypothalamus (which is in the brain), react to this drop by enhancing your appetite, therefore, you start to feel hungry almost all the time.

3 – Low body fat can result in hormone imbalances

This is a very likely outcome for women. Again, it has something to do with the hypothalamus. By knowing that the lipid percentage has dropped low, it decreases a certain hormone that that plays part in the pituitary gland, which on the other hand reduces other hormones that affect the ovaries. As a result, the ovaries lower the production of progesterone and estrogen, which might cause problems with the menstrual cycle, and potential infertility.

Besides women, men too can experience a bad aftermath from having too low body fat index. Males can have their testosterone levels dropped, which naturally isn’t pleasant for any man who wants to have a wholesome life, because it leads to loss of sexual desire, low production and low quality of sperm, as well as difficult buildup of lean muscle tissue.

4 – You may become more susceptible to heart problems

This is another probable health-harming consequence that could occur. Kevin Campbell, M.D who works at the American College of Cardiology, says that extremely low body fat percentage can stir up the normal functions of the cardiovascular system. In a research published in the International Journal of Sports Physiology and Performance, when bodybuilders prepared for a competition by additionally lowering their body fat, their heart rate dropped to 27 beats per minute. Such condition is called bradycardia and can lead to vertigo, fainting, or even worse – cardiac arrest. Furthermore, according to Dr. Campbell very low lipid index can make electrolyte imbalances, and low-caloric intakes can be the cause of arrhythmia or sudden cardiac death.

5 – You feel like a wreck and your workouts feel lame

When you exercise, your body utilizes carbohydrates to produce energy. Doctor Campbell says that somewhere after 20 minutes of hard exercising, when carbs start to get depleted, the body refers to fat as an energy source. And if you have too little fat your sport activity will suffer, making you feel weaker and perform poorly.

6 – Your muscles recover harder from athletic performance

So not only will your workouts not be on the necessary level, the body itself will have a hard time regenerating upon them, making you experience muscle pain, stiffness, and you would feel as if you were not in shape. That means even if you do have a super lean figure, you won’t be able to extract the full benefit from your sport activity. According to Mike Nelson, PhD, C.S.C.S, who is an exercise physiologist, when your body fat percentage is low, so are your levels of glycogen (stored carbohydrates) in the liver and muscles. Glycogen is essential for recovering your body from physical activities.

7 – Muscle gain becomes nearly impossible and muscles get weaker

We already noted that when body fat is too low, testosterone levels get dropped critically, muscles become weaker and recover slowly. Following all of this, even in Dr. George Fear’s opinion, lean muscle gain has a snowball’s chance in hell. In the same study published in the International Journal of Sports Physiology and Performance, the bodybuilders who wanted to significantly drop their body fat, also had their body mass and strength dropped too, months before the competition. It took them more than half a year to regain the lost muscle.

8 – Your muscles become more fragile

That’s because when reach the critically low levels of body fat and weight as a whole, you hamper the body’s ability to absorb vitamins and minerals, among which are vitamin D, calcium and vitamin K, and as you might know, these nutrients are essential for a healthy bone system. Dr. Fear says that athletes in weight-classes sports who try to reach maximum stage of leanness, have been shown to have lower bone density, some even develop osteoporosis.

9 – Your skin appearance worsens

Essential omega fats are also necessary for a healthy, glowing, moisturized skin. Speaking for skin moisturizing, extra-lean people often don’t consume enough water-storing carbohydrates, therefore, dehydration is common in them. In dehydration mode the body sucks the water out from the skin, and distributes it to the vital organs, which leads to it being dry and spotted.

10 – You feel cold

Another statement of Dr. Campbell is connected to this point. He says that since body fat has a role in maintaining body temperature and insulating the organs, those with inordinately low body fat index often complain about being cold. The internal temperature can also be unbalanced due to thyroid dysfunctions which too are incidental to men with extremely low body fat.

11 – Your immune system grows weaker

Very low energy intake and body fat are linked to higher cortisol levels which tampers with the immune system. This tremendously increases your risk of catching a cold, another virus or bacterial infection.

12 – You find yourself having severe mood swings more often than usually

According to Dr. Campbell, sufficient essential fatty acids in the brain are required for proper neurologic functions, brain development and overall brain health. If those fats aren’t at disposal of the brain to use for energy, bad mood starts to creep a lot more often than you would like, and depression seems a lot more likely.

13 – You may start having brain fog

That’s also a result from the lack of essential fatty acids within the brain. Omega fats are absolutely indispensable for normal brain functions, and if the brain doesn’t receive enough of them, you are very likely to start experiencing bad concentration, mental fatigue, and slow thinking. That will definitely not help you fulfill your daily tasks.

14 – Problems with your social life

Dr. Fear says that having too low body fat index requires certain lifestyle changes, which most people aren’t inclined to make. For instance, you have to cut alcohol intake, eat only properly cook food, and count every gram of food and calorie you consume. That’s not an easy job, plus you don’t get paid to get it done.

These are the risks of having extremely low body fat levels, and everybody who aims at getting leaner than usual should consider them wisely before putting their body under such stress. Remember friends, health is easily shaken, so preserving it should be every person’s top priority. Achieve the results you want, but do it the smart way, and for your own sake don’t cross the boundaries of what’s considered a healthy norm.



Certified SportsNutritionist and Health Enthusiast

I’m Nick – a nutrition enthusiast who takes his healthy lifestyle at heart, and an avid Brazilian Jiu-Jitsu athlete. Being the main author and founder of, I’m constantly looking to expand my experience and knowledge of food, health, sport, and organic living, so I can become the best version of myself, and help others achieve the same.

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