BMJ Group Medical Reference
This information is for people who have high blood pressure. It tells you about how losing weight can help keep your blood pressure under control. This advice is based on the best and most up-to-date research.
Does it work?
If you have high blood pressure and are overweight, losing even four or five pounds (a couple of kilograms) may help to bring your blood pressure down.
If you are being treated for high blood pressure, losing weight may make the treatment work better. And it may reduce how much of the medicine you need.
Having high blood pressure increases your risk of having a heart attack or a stroke. So far there isn't any evidence that lowering your blood pressure by losing weight will reduce this risk.
There's no advantage to losing weight if you are already at a healthy weight.
For more, see our information on treatments for obesity.
What is it?
To lose weight, you have to eat fewer calories than you burn. Just how many calories you burn depends on things such as your body size and how active you are.
Doctors tend to use two measurements to work out whether you are overweight:
Your body mass index (BMI). Your BMI relates your weight to your height. This gives an estimate of your body fat. If your BMI is more than 27, you have a higher risk of getting high blood pressure.  You can use our calculator to work out your BMI.
Your waist measurement. According to US guidelines, if you're a woman and your waist is more than 88 cm (35 inches) you are considered overweight. If you're a man, and your waist is more than 102 cm (40 inches), you are considered overweight. 
How can it help?
Studies have shown that people who lost 3 percent to 9 percent of their weight reduced their systolic pressure (the top number) and their diastolic pressure (the bottom number) by an average of 3 points more than people who did not lose weight.  (To find out more about the numbers, see Understanding your blood pressure reading.)
If you take tablets for your blood pressure, losing some weight may help them work better. This means you might be able to cut down the dose you need to take or the number of different drugs you need. 
How does it work?
Doctors don't know exactly why losing weight helps lower blood pressure.
Can it be harmful?
There is no evidence from the research that losing weight will hurt you.