Being overweight is an important and reversible cause of high blood pressure, particularly in young people under 40. If you can get your weight down and keep it down so that you have a body mass index of 25 or below (body mass index is calculated by dividing your weight in kilograms by the square of your height in meters) then you have a good chance of normalizing your blood pressure. Although middle-aged and older people may get some fall in blood pressure with a fall in weight, it is likely to be much less than in younger people. Still, many overweight people whose blood pressures fail to come down with apparently adequate medication find their drugs are more effective once they lose a stone or so (about 6 kilograms) in weight. You must also bear in mind the possibility that a standard sphygmomanometer cuff applied to a large arm is probably giving misleading blood pressure readings. Simply using an outsized cuff that fits correctly will often bring readings down by about 20 mmHg.
If you are overweight, getting your weight down will almost certainly also bring your blood pressure down if you are under 40 and probably will even if you are older than that. It will reduce your risk of developing other health problems with being too fat, such as diabetes. Although the connections between the causes of high blood pressure and the causes of diabetes are mot yet fully understood, they are certainly important: people with high blood pressure are more likely to get diabetes later in life. What you really need to consider is not just what you weigh, but how much body fat you have. Simply weighing yourself will tell you if you are overweight, but it will tell you nothing about the proportions of fat and muscle in your body. It is excess fat, not muscle, which causes high blood pressure and increases the risks that have to do with being overweight. To improve your general health, to reduce blood pressure and the risk of coronary heart disease or stroke, to prevent diabetes (or to improve control of diabetes if you have it already), you require not only energy balance (calories in equivalent to calories expended; don’t eat more calories than you use), but a higher energy throughput (more energy about in and out) – which means taking more exercise as well as watching what you eat.
The combination of a sensible diet and regular exercise will build muscle and reduce fat stores. Do not be discouraged if you do not immediately seem to lose weight when following such a program – while you are replacing your fat with muscle, the change will not readily show up on the scales. In the longer term, you will see your weight fall. What is important for you to remember is that losing weight on a calorie-reduced diet but without an exercise program will have less effect on your blood pressure (and the accompanying risks of coronary heart disease and stroke) than the same weight loss achieved with an exercise program.
Michael Russell Your Independent guide to Blood Pressure