May 24, 2022

Body Mass Index or BMI is the quickest and the most popular method used to assess someone’s health based on their weight. The formula for calculating the score only consists of the body height and mass, but many variables affect it. One of them is age. So let’s explore does BMI change with age?

How Does Body Weight and Height Change with Age?

A person’s body weight increases with age. Especially after you are 30, you start losing muscle tissues, which get replaced by fat. Of course, this can be delayed with proper diet and exercise, but the process continues until 55 for men and 65 for women.

On the other hand, you also lose height as you grow older. A study shows that, on average, men lose 3 cm, and women lose 5 cm of their height between 30 and 70 years of age.

BMI and Age Trends

BMI and Age Trends

The average BMI for women between 20 and 28 years old is 27.5. On the other hand, for ages between 60 to 69, it is 29.6.

The same trend can be seen in men, as the average BMI in the 20 to 29 year age group in the USA is 26.8. For people between 60 to 69 years, it is 29.

Also, as per the Centers for Disease Control and Prevention, the average weight gain for adults is 1 to 2 pounds a year from early adulthood through middle age.

You see, as you grow older, your BMI increases, and it may be more difficult to stay within the healthy limits.

Reasons for Weight Gain With Age

These are the reasons that make it challenging to maintain a healthy body weight as you age:

Hormonal Changes

Both men and women go through hormonal changes which affect their body composition. For women, significant weight gain happens after menopause (between 40 and 50 years), which causes them to lose estrogen and accumulate more weight around the belly.

Similarly, men start losing testosterone at around 40 to 45 years of age, which is the hormone responsible for fat regulation. This makes their body less effective at burning calories, due to which more food converts to fat than when they’re young.

Slowed Metabolism

Fat requires fewer calories to maintain than muscle. In other words, as you grow older, you will struggle to lose or maintain weight even when you are eating lesser than when you are young.

The slowed metabolism affects everyone but is seen more in women than in men. This is because women naturally have more body fat than men.

Lifestyle Changes

Changing lifestyles can also be attributed to the change in BMI with age. With work and family, people are less likely to have enough time to exercise or maintain a healthy lifestyle.

Even after retirement, people become reluctant to exercise. After all, after fulfilling the important things in life, everyone would want to relax and enjoy themselves more, and any job involving weight loss isn’t really that fun.



When you grow older, your brain becomes less adept at regulating hormones, decreasing your body’s defense against stress. In other words, it ends up producing more cortisol (stress hormone) when you are under mental pressure. 

Cortisol is naturally known to increase appetite. This also explains the increased stress eating in older adults. Furthermore, according to various studies, the impact of age on increasing cortisol is more in women than men.

Body Mass Index And the Elderly

While it may seem counterintuitive, for age groups over 70 years old, a higher BMI between 25 and 27 seems to be better than the range for younger adults.

A body’s ability to absorb nutrients becomes weaker as it gets old. Hence, even with a normal BMI score, you may not have enough nourishments to combat illnesses such as osteoporosis and cardiovascular disease.

How to Maintain Normal Weight With Age?

There really are only two ways to maintain a healthy weight; diet and exercise. 

Eat Healthy Food

Here are some pointers for diet for older adults:

Avoid Empty Carbs

Foods such as soda, baked goods, and candies that overload you with carbohydrates but don’t provide other nutrients are known as empty carbs. You need to avoid them as much as possible for any kind of positive health outcomes, including for a more balanced Body Mass Index distribution.

Replace More Carbs with Protein

As you grow older, you have to put emphasis on gaining and maintaining a healthy skeletal muscle mass. This can only be achieved by having adequate protein in your system. 

Furthermore, as you already have more fat when you’re old, you won’t need as many carbohydrates as when you needed when you were younger. But of course, don’t disregard any nutrient; just find the perfect balance for each.

Focus on Vitamin D and Calcium

You should aim for at least 10 to 30 minutes of daily sunlight for optimal vitamin D. As for food, choose items that have added Vitamin D and Calcium to keep your bones strong. You can consider taking supplements as well. 

Don’t Forget to Rehydrate

The sense of thirst decreases with age. But this doesn’t mean your body requires less water when you grow old. According to the U.S. National Academies of Sciences, Engineering, and Medicine, men should drink 3.7 liters, and women should drink 2.7 liters of fluid every day.

Eat Naturally Occurring Food

Vegetables, fruit, and whole grains should be given the most preference. As your age increases, you should cut down on packaged food or anything ‘artificial’.

Bonus Tip: Replace table salt with Pink Himalayan Salt. The latter is a better source of nutrients, consisting of up to 84 minerals.

Regular Exercise

Regular Exercise

Refer to this table for the recommendation for physical activity given by the World Health Organization:

Age GroupRecommended Amount of Physical Activity
Children and Adolescents (6 to 17 years)Sixty minutes of moderate to vigorous physical activities.
Adults (18-64 years)At least 150 minutes a week of moderate physical activity, for example, jogging. 
Older Adults (65 years and more)Like other adults, older adults should also get at least 150 minutes a week of moderate exercise. 
However, they need to focus more on activities to improve balance, for example, climbing stairs and cycling.

Bottom Line

As you age, your body starts accumulating more fat. Hence, this may cause significant differences in the Body Mass Index. However, you don’t need to worry about it a lot. As long as you know what to eat and exercise properly, you can attain a healthy BMI no matter how young or old you are. 

BMI Calculator