A BMI of 31 falls into the obese body mass index category, although it is on the lower end of the obese classification, and yet, it’s actually a rather average BMI.
Still, despite the fact that many people nowadays have a BMI that exceeds 31, people who have a 31 BMI should still seek to lose weight sustainably so that they can improve their health.
See How Your BMI Compares:
Is a BMI of 31 bad for women?
Is a BMI of 31 bad for women? Yes, a BMI of 31 is definitely bad for women because such a high body mass index could put a woman at risk for chronic diseases like diabetes and cardiovascular disease.
Surprisingly, a 31 BMI score isn’t that much higher than average for a female. But that fact granted, a body mass index of 31 is still comfortably in the obese category and, therefore, should be reduced if possible.
While some research does suggest that large BMI losses can lead to an increased mortality risk in older adults, this might be because those who shed lots of weight lack muscle mass. 
So if you want to reduce your BMI, you should perform resistance training as well as cardiovascular exercise so that you can strengthen your muscles and bones and build a more resilient body.
How bad is a 31 BMI for men?
Is a BMI of 31 bad for men? Even though a BMI of 31 isn’t that much higher than average for a man, a body mass index of 31 is still considered obese for males.
While it is technically possible (but extremely unlikely) for a BMI 31 man to be fairly lean, it suffices to say that most people don’t have a BMI of 31 because they’re too muscular.
Sure, you can have plenty of muscle mass at a BMI of 31. But it’s not the muscle that’s responsible for your obese BMI; it’s your body fat in combination with your lean mass.
Some active men (such as recreational bodybuilders) may “achieve” a 31 BMI if they bulk for too long or overeat in an attempt to gain as much size as possible.
On the other hand, a man could have very little muscle mass but lots of body fat, which might result in an obese BMI.
What does a body mass index of 31 look like?
Generally, a BMI of 31 looks overfat because such a BMI is considered obese. However, the more muscle a person has, the leaner that a body mass index of 31 will naturally look.
However, in most cases, lean isn’t a word that you’d use to describe the physique of a BMI 31 person.
A BMI of 31.1 is on the lower end of the obese category but is still too large for a person to enjoy their best health.
If you have a BMI of 31.2, then you’re likely putting your health in danger by carrying too much body fat, something that’s particularly bad when the fat accumulates around your waist.
A 31.3 BMI is considered obese for men and women. Although BMI doesn’t directly measure body fat, almost everyone with a BMI of 31.3 has an excess amount of adipose tissue on their body.
Those who have a 31.4 BMI are comfortably in the obese body mass index category and should try to lose weight so that they can improve their cardiometabolic health.
A 31.5 BMI is larger than average for both females and males, meaning that a man or woman who has a BMI of 31.5 is risking their health by maintaining such a high body mass.
If you have a BMI of 31.6, then you’re considered obese for a person of your height. While you can certainly be muscular with a 31.6 BMI, few people have a body mass this high due to muscle alone.
A BMI of 31.7 falls into the obese category and is a strong sign that the BMI 31.7 person needs to lose fat. Someone of this size, even though they are heavy, may also benefit from gaining more muscle mass, especially in conjunction with fat loss.
If you’ve got a 31.8 BMI, then your body mass index puts you in the obese category. Of course, many people have higher levels of obesity than this, but you should still aim for sustainable weight loss if you have a BMI of 31.8.
A 31.9 BMI is very high and, as such, is considered obese due to the fact that a BMI of 31.9, if maintained or increased, can negatively affect many areas of your health.
The verdict: How much weight should you lose if you have a BMI of 31?
The precise amount of weight that you should lose in pounds or kilos depends on your body weight as well as your BMI.
Since people with the same BMI can have very different body weights, it’s not possible to give specific weight loss recommendations.
Nonetheless, research shows that it is possible for obese individuals to lose weight, at least in the short term. 
If you have a BMI of 31, you should aim for sustainable weight loss so that you can make real, lasting changes in your life that, in time, will help you to achieve a healthy body weight.
Restricting your calorie intake by 500 calories per day is a good place to start. But if you’re really heavy, then you might even be able to see better results by employing—under the supervision of a doctor or nutritionist—an even larger calorie deficit.
- Myrskylä, M., & Chang, V. W. (2009). Weight change, initial BMI, and mortality among middle- and older-aged adults. Epidemiology (Cambridge, Mass.), 20(6), 840–848. https://doi.org/10.1097/EDE.0b013e3181b5f520
- Nicklas, J. M., Huskey, K. W., Davis, R. B., & Wee, C. C. (2012). Successful weight loss among obese U.S. adults. American journal of preventive medicine, 42(5), 481–485. https://doi.org/10.1016/j.amepre.2012.01.005