The IU diet is very restrictive, and one has to be very careful when sticking to it. In addition to being highly restrictive, the diet is very difficult to stick to. Sticking to it for a long time can affect your brain and overall health. Hence, it would be best if you did not stick to the IU diet for a long time. If you are new to restrictive diets such as the IU diet, you should use the 5:2 approach. This means you have to take your regular meals for five days and follow the IU diet for two days. This would ensure your body gets all the nutrients it needs.