Dr Bernstein is the pioneer in What to Eat, Dr Westman added a When to Eat component by encouraging Time Restricted Eating, (OMAD is OK) and now Dr Fung extends the When to Eat to full days of fasting. If you are T2 and want to remove stored fats and glucose quickly, add IF. They all use the same VLC 20-30g diet and Food list from Dr Bernstein, but there is a choice about When. Eat 3 x day in 6-12-12, or eat less than 20g whenever you are hungry in a day, or fast multi-day and eat LC whenever you decide to eat.