Calculating waist-to-height ratio
Measure your height using the same units you measured your waist circumference in, (either centimetres or inches). To work out your waist-to-height ratio, divide your waist measurement by your height measurement. Use a calculator or your phone to do this (waist ÷ height = ratio). The answer should be a decimal number.
Here is how waist-to-height ratio affects your health risks.
- 0.4 to 0.49 = healthy amount of fat around your middle, no increased health risks
- 0.5 to 0.59 = increased fat around your middle, increased health risks
- 0.6 or more = high amount of fat around your middle, further increased health risks
A good way to think of it is that you should try to keep your waist measurement to half your height (this gives you a waist-to-height ratio below 0.5).
These categories are for people with a BMI under 35kg/m2, and are the same no matter your sex and ethnicity. They also apply to people with high muscle mass.
Reasons for weight gain or loss
Changes to your weight are mainly down to the balance between calories you take in through food and drink, and calories you use in activity. Put simply, you'll:
- gain weight, if you take in more calories than you use up
- lose weight, if you use up more calories than you take in
- maintain your weight, if you balance the calories you take in with the calories you use up
Other factors can also make a difference. For instance, your genetic make-up can sometimes make you more likely to put weight on.
Other things that can affect your weight include the following.
Getting older. As you get older, you lose muscle mass and gain body fat instead. Your metabolism also slows down and you have lower energy requirements. This makes it easier to put on weight.
Menopause. Weight gain during menopause may be partly due to falling levels of the hormone oestrogen in your body. This is in addition to the changes that happen to your body as you get older, described above.
Malnutrition in old age. Although weight gain is common as you age, people in the oldest age groups (above 75) are also at risk of becoming underweight. This may be due to difficulty eating, cooking, and preparing food. Older people may also be more likely to have a poor appetite and to have health conditions.
Medicines. Certain medicines, including steroids, some types of contraceptives, and some antidepressants can cause an increase in weight. Other medicines may reduce your appetite, change your taste or affect your digestive system, leading to weight loss.
Medical conditions. Conditions that affect hormone levels, such as polycystic ovary syndrome and underactive thyroid can cause weight gain. Meanwhile, living with a long-term health condition like diabetes or kidney disease can be associated with weight loss. Digestive problems, depression and cancer can also cause weight loss.
Reaching a healthy weight
If you're currently over or underweight, making some changes to get to your ideal weight will really benefit your health.
If you’re overweight or obese
If you’re overweight, aim to reach a healthy BMI and waist-to-height ratio by losing weight gradually. A good target to aim for is losing about 0.5 to 1kg (1 to 2lb) a week.
To lose weight, you'll need to use up more calories than you take in from food and drink. Reducing your calorie intake and increasing how much activity you do can both help.
It's worth thinking about the following points.
- What you eat. Eating foods high in fat and sugar will make you more likely to put on weight.
- How much you eat. Many people eat much larger portion sizes than they need.
- How you eat. Eating quickly or when you’re doing other things, like watching TV, can result in overeating. Try to eat slowly, focusing on your food.
- How much alcohol you drink. Alcohol is high in calories and can contribute to weight gain.
- How much activity you do. Looking for ways to be more active can help you to lose weight and keep it off.
If you’re underweight
Being underweight means you might not be getting all the nutrients, vitamins, and minerals that your body needs to be healthy.
To put on weight, you will need to try to increase your calorie intake by eating a balanced and nutritious diet.
Healthy ideas to boost your calorie intake and increase your weight include the following.
- Try to eat little and often. Aim to have nutritious snacks in between meals, like cheese and crackers, creamy yoghurt, flapjacks, nuts, and seeds.
- Avoid low fat and diet versions of foods and drinks. Go for higher fat options of milk, cheese, cream and other foods, until you reach your ideal weight.
- Foods that are high in protein can help to build you up. These include meat, fish, eggs, nuts, beans, pulses, and meat-free protein alternatives.
- Add cheese to sauces, potatoes and vegetables, and add milk powder to mashed potato, puddings and soups to increase energy and protein.
- Have milky drinks, like hot chocolate, malted drinks, smoothies, and milkshakes.
- Have some ready meals and other foods that are easy to snack on for times when you don’t feel up to preparing food.
If you have a health condition, talk to your doctor or a dietitian first before making any changes to your diet.