Training underweight woman measuring

Published on April 17th, 2013 | by Joe Starks


The Many Faces of Fitness: Fitness for Underweight People

Underweight people tend to have less energy than their normal weight peers. Due to that, they sleep more or depend on more energy boosting substances and can easily feel dizzy or get a headache when exerting themselves. It is impossible to be eating healthily and to be underweight. To be a healthy individual you don’t just need vitamins and minerals, you absolutely need to get enough macronutrients to sustain you at a weight that offers you the minimum body fat needed to function properly.

The more underweight you are the worse the symptoms usually are. Emotionally there is often a lack of self esteem, especially in men, due to the bony appearance and physical weakness. Even women who love their size zero will feel the long term effects of being underweight later in life when the deficiencies will do their devilish work on the body.

All these factors make it so that underweight people often avoid exercise or do it secretly without guidance.

When you wish to become fitter as an underweight person it is impossible not to address the missing weight. To gain muscle you need energy or your body will simply eat up its own muscle to help you move, since there are no fat storages left to get energy from. Starting an exercise regime as an underweight person without the right diet and guidance can actually cause you to lose muscle that way.

The diet

You do not need to get fat to exercise. The fitter you are, the less body fat you actually need to function properly. But to grow that muscle, you do need more calories than what an underweight person usually would consume. The calories should not come from just any source either. It is best to add some lean protein to the diet and cover essential fatty acids needs. Sugars should be consumed only at the level where the body will use the energy to grow lean mass and sustain the effort of exercising.

If you are extremely underweight, then you should not do any exercise at all until you have gained at least as much weight you need to be healthy. People who suffer from eating disorders should not get advice from the internet but instead seek help from specialized physicians as soon as possible.

For those who are only a little underweight the above program should work just fine without any problems. It is good to address any issues that cause you to under-eat. Stress, a busy social life and a general indifference towards food are the top reasons people become underweight. Find a way to overcome those and commit to a muscle building diet.

The Exercises

People who are too thin are also generally weaker than similar normal weight people. This happens because the body tends to burn up its own muscle as fuel once your fat reserves have gone too low. Someone who is only a couple of pounds underweight might not feel this at all, while others who miss over ten or twenty pounds would be stronger if they weren’t so underweight. You should note that athletes sometimes might look underweight without that necessarily being true. Female rhythmic gymnasts for instance might look very tiny and underweight, but it is often just an illusion created by a low body fat percentage, a small frame (most of these women are quite young and short) and a lot of strong muscle built for endurance.

To start exercising with no energy reserves in your body is like muscle-suicide. You’d just shock your body into burning the little muscle you have. This is why the diet must come first and afterwards the fitness regime. The exercises must start at a low intensity and build up over time. As soon as you easily can complete the routine without feeling tired you should start adding exercises or increase the difficulty of the exercises you already do.

Good choices for an underweight person are aerobic or mixed aerobic-anaerobic exercises to build up endurance before you build strength. Some examples are aerobic dancing (and dancing in general), martial arts, tennis, swimming, jogging, hiking and briskly walking.


To become fit as an underweight person you first have to solve the problems that cause you to be underweight. Just like with overweight people nobody should stay underweight. On the contrary, one should always strive to be within the normal weight range. Fitness can help you get to a normal weight by gaining muscle instead of pure fat, but to gain muscle extra calories are needed. A good muscle building diet together with a moderate intensity fitness regime should do the trick.

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3 Responses to The Many Faces of Fitness: Fitness for Underweight People

  1. ofennnwu says:

    I am nineteen year old female with 158 cm height and 39 kg weight. I know i am severely underweight for my case, my bmi is 15.89 and i am naturally skinny all of my life. I tried to eat a lot but sometimes i have the tendency to puke back the food i eat and lose my appetite. Every single meal is a battle for me to finish. Always i find my mouth is actively salivating but i dont feel hungry. What should i do? I tried to eat healthy and i want to gain healthy mass muscle and getting toned. some suggests i should take a protein shake and supplement. Is that necessary?

    • Lucie Courtney says:

      I am too 19 and got a similar height and weight as you.
      I can’t eat big meals it feels physically impossible.
      Try to eat little but often.
      Eat dairy, lean meat, cheese, carbs like bread pasta and potatoes.
      And sometimes drinking (not alcoholic) but drinking in general can fill your stomach.
      I prefer to drink so maybe blend meals in smoothie form?

      I’m in the same boat as you it’s awful.

      • Firas says:

        Hi, I was an underweight guy. My BMI was !6.4. Thank God I somehow ended up in dietetic study. Two tips for you:

        The key is to eat at a ‘consistent’ frequency. I know some of my friends sharing the same problem and saying they are eating frequent enough. But further probing reveals that there are ‘some’ days they skip one/two main meals (and back it up with some calorie-light snacking). And the ‘some’ days happen almost every week. So, commit yourself to a ‘real’ consistent meal frequency. It can be three main meals and the-always-forgotten single snacking.:)

        For your appetite, as you gain fat you will notice that you ‘can’ become hungry. Because some appetite hormone is regulated by our ‘fatness.’ If you find it so difficult to eat, opt for milk! Chocolate/malt drinks are great too. And never afraid of oily dishes, they are your allies! Unless you’re currently having familial hypercholesterolemia that you need to watch out for your cholesterol level (but cholesterol isn’t the only fat okay).

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