Do you need to do this? 4 stone in 3 months is approximately 4 and a half pounds you'd have to lose consistently and that's very extreme. A healthy weight loss is between 1-2 pounds per week. Losing a lot of weight in a short period of time is not healthy and also not sustainable and it's much easier to pile the pounds back on afterwards. 2 years ago I lost 4 stone but I did that in 5-6 months of regular exercise and eating in a calorie deficit, with the help of my boyfriend who is a personal trainer. So I definitely would not recommend it.