In western countries 80 % of patients with ischemic heart disease (IHD) are overweight (BMI \> 25). Weight loss using a low energy diet (LED, 800 - 1000 kcal/day) has been shown to induce a considerable weight loss in obese but otherwise healthy patients and to reduce the risk of cardiovascular disease and diabetes in these subjects. Additionally, a British study using a very low energy diet (VLED, 600 kcal/day) to obtain weight loss, has shown that subject with diagnosed type 2 diabetes had their blood glucose normalized after an 8 week VLED. However, the effect of LED has never been examined in overweight patients with IHD.
Several studies have shown that patients with IHD have a beneficial effect of exercise training regarding mortality and reduction in cardiovascular risk factors. A Norwegian group has shown that aerobic interval training results in the biggest increase in maximal oxygen uptake (VO2max). A high VO2max is correlated to decreased mortality in patients with IHD.
In conclusion, weight loss and exercise are known strategies in preventing progression of IHD and development of type 2 diabetes in these patients, however a head-to-head comparison of the two methods has never been made and it is unknown which intervention is the most effective in improving cardiovascular risk profile. Furthermore, several mechanisms behind the known beneficial effect of these interventions are unknown.
