There isn’t a clear answer to this question. For example, studies carried out on participants with type 2 diabetes suggest that fasting can help manage the disease. That’s obviously a good thing. There have also been smaller-scale studies suggesting that fasting can have a positive effect on cardiovascular diseases. However, if you suffer from a disease like any of the above, you should talk to your doctor and explore the avenues available to you. Because as an enlightening Guardian article points out, a combination of insulin drugs and fasting can be lethal.
The same article points out that there can be other health benefits to fasting, including a sort of ‘cleansing’ of cells – when the body is deprived of food and starts ‘eating’ itself as a result. There could be some substance to this, yet most of the studies around fasting are carried out on mice, not humans, and as we know, there are vast complex differences between rodents and homo sapiens. In other words, the jury’s still out on the health benefits of fasting.
Perhaps your physical and mental energy would be best used in planning out regular exercise and nutritious food to fuel your body so that it performs at its best. If you’re looking to fast to lose weight for health reasons, studies have shown that a low-calorie-diet actually has the same effect as the more restrictive 5:2 diet (where you eat as usual for five days a week and pair it back considerably during the other two). So even when it comes to cutting down on calories, there isn’t substantial evidence to prove the benefits of fasting.