Healthy weight and exercise
Published by Bupa's health information team, healthinfo@bupa.com, April 2008
This article explains how to work out whether you are a healthy weight and how you can manage your weight through exercise.
The risks
Two-thirds of men and women in the UK are now either overweight or obese. Obesity doubles the risk of dying early and increases your risk of developing:
- heart disease
- type 2 diabetes
- high blood pressure
- gallstones
- arthritis
- some types of cancer
- musculoskeletal problems
- psychological problems
Your body's composition
Talking about just "weight" is really an oversimplification. What counts is not your total mass, but what your body is made up of - your body composition.
Your body is made up of lean body tissue (muscle, bone and internal organs) and stored body fat. The balance between these components in your body is important. For example, you may be the right weight for your height but be carrying too much body fat. Although we all need some body fat, excess fat can lead to health problems.
It's healthier to have a higher proportion of lean tissue, which is mostly muscle. Muscle weighs more than body fat. If you do a lot of weight training, you may be classed as overweight because you have well-built muscles, but this is healthy.
Fat distribution
Your body needs to store some fat to function normally. Fat is distributed differently in different people.
In "apple-shaped" people, fat is stored deep below the skin in the stomach area. Too much fat here puts you at a higher risk of heart disease, high blood pressure, type 2 diabetes and some cancers. You are apple-shaped if your waistline tends to grow when you put on extra pounds.
Pear-shaped people mainly carry body fat under the skin around the hips and thighs, and have a lower risk for these illnesses. You are pear-shaped if your hips and thighs tend to get bigger as you gain weight.
Am I a healthy weight?
There are various ways to find out whether you are a healthy weight and build, or if you carry too much fat - ie you are overweight or obese.
It's best to use a combination of body mass index (BMI) and waist size.
Body mass index (BMI) and waist size
Doctors, dieticians and other health professionals use body mass index (BMI) to help find out whether you are a healthy weight for your height. You calculate your BMI by dividing your weight in kilograms by your height in metres and then dividing by your height again. Try using our BMI calculator.
The ranges of BMI values for different weight categories are:
- underweight to less than 20
- healthy weight to 20-25
- overweight to 25-30
- obesity I to 30-35
- obesity II to 35-40
- obesity III to 40 or more
BMI is not suitable for children, young people or older people, or during pregnancy.
Another drawback of BMI is that it does not take your body composition into account. This means that even if your BMI is within the normal range, you could be carrying too much fat. Equally, you could be heavily muscled, with little body fat. This may put your BMI above the healthy range even though you are very fit and healthy.
That's why you should also look at your waist size. For good health, this should be less than 37inches/94cm for men and less than 31.5inches/80 cm for women. So your health is not at risk if your waist measurement is low, even if your BMI is in the overweight category.
How else can you tell if you have too much body fat?
There is no recommended amount of body fat for optimum health, and it's normal for body fat to increase with age. But doctors consider anything between about 10 and 20 percent for men and 20 and 30 percent for women to be healthy. You would expect to be nearer the lower end of the range if you are young and the upper end if you are over 60. It's unhealthy for body fat to drop below 5 percent for men and 12 percent for women.
Athletes' body fat tends to be lower than average, but this varies depending on the sporting activity. For example, runners, cyclists and track athletes tend to have lower body fat than swimmers and tennis players.
If you go to a gym or have a health assessment, you may be offered a body fat measurement. There are a number of ways to estimate your body fat percentage, including:
- the skinfold test, where your health professional uses callipers to measure the depth of fat under your skin in different parts of your body
- bioelectrical impedance analysis, where your health professional sends a painless low current through your body, which passes more easily through muscle than fat
These tests are not always reliable so doctors don't recommend them as an accurate way to find out if you are carrying too much fat.
Exercise and healthy weight
Exercise can help you lose fat and build muscle. The best way to lose weight if you are overweight or obese is to combine a lower-calorie diet with regular exercise. Physical activity burns calories, so the more you do, the more weight you will lose. It affects the composition of your body by helping you to lose fat and hang on to lean tissue - which is mainly muscle.
Experts recommend a gradual weight loss of up to two pounds (one kilogram) a week. To achieve this, reduce your overall calorie intake by about 500 to 600 calories per day, aiming for about 1,500 calories for women and 1,800 for men, and exercise regularly.
The recommended minimum is 30 minutes of moderate exercise a day, five days a week. But you might need to do more to prevent obesity - 45 to 60 minutes on five days. And if you used to be obese and have already lost weight, keeping the weight loss going might need 60 to 90 minutes of activity on five days a week.
Combine aerobic training such as running, with resistance exercise such as weight training to build muscle.
Key points
- It's not just your weight, but your body's composition that determines whether you are overweight.
- Work out if you are a healthy weight by calculating your BMI.
- Measure your waist - it should be less than 80cm in women and less than 94cm in men.
- Exercise helps you lose fat and build muscle.
Further information
- Weightwise
www.bdaweightwise.com - Food Standards Agency
www.eatwell.gov.uk - British Nutrition Foundation
020 7404 6504
www.nutrition.org.uk
Related information
- Benefits of exercise
- Exercise - what type, how much?
- Carbohydrates and exercise
- Energy, exercise and weight control
- GI approach to weight control
