Healthy calorie deficit is depends on one's weight. There is a rule of thumb: it is considered healthy to lose about 1% of weight per week. This gives us 40% pe

Healthy calorie deficit is depends on one's weight. There is a rule of thumb: it is considered healthy to lose about 1% of weight per week. This gives us 40% per year. This guy lost 41% in a bit less than 11 months and his progress is quite linear, so I beleive he is basically okay, maybe a little on the rough side, but far from the extreme fasting.