If you have a heart condition you might want to think twice before embarking on a crash diet.
A new study out of Oxford in the UK has found that crash diets might well be effective in weight loss, reducing blood pressure and reversing diabetes, however in the initial days they aren’t doing your heart any favours.
The research team, led by Dr Jennifer Rayner from the Oxford Centre for Magnetic Resonance studied the effect of very low calorie diets, 600-800 calories per day, on the heart. There has been plenty of great research into the affect of low calorie diets on weight loss and reversing diabetes, however their effect on the heart hasn’t been studied in detail until now.
Twenty one obese participants were given this very low calorie diet for eight weeks, and MRIs were used to track the subjects heart muscle and function during the trial. The MRIs indicated that after one week, the fat content of their hearts actually increased by 44%. A rise in heart fat is associated with declining heart function as it affects the ability of the heart to pump blood. By week eight however, the participants were tracking with improvements in body fat and cholesterol measures, including heart fat, which you would expect to result in improvements in heart function. So the subjects heart functions actually got worse before they got better.
It appears that those early days of severe calorie restriction, fat is being released by various parts of the body into the blood. This fat is being taken up by the heart muscle, which is affecting its function. Once the body adjusts to a longer period of calorie restriction the fat content of the blood and heart reduces, and the heart condition improves.
Dr Rayner maintains that there are many benefits of low calorie diets for people with obesity, diabetes or other heart conditions, so they shouldn’t be avoided all together. However, if you already suffer from a heart condition it’s a good idea to work with a medical practitioner before embarking on a very low calorie diet, to avoid any nasty surprises in the early days !