Summary: Each day of the GM diet has specific rules on which foods are permitted. Fruits, vegetables, meat and milk are the main foods allowed.
Any time you reduce your calorie intake, your body looks for other sources of fuel. This causes your body to break down glycogen, an energy-storage molecule found in the liver and muscles.
The diet is also not well-balanced and may lead to feelings of deprivation and hunger on some days, due to the varying amounts of macronutrients it provides.
Summary: The GM diet is somewhat flexible on the foods you can choose. It encourages you to eat more fruits and vegetables, while limiting sugar-sweetened beverages and alcohol.
Proponents of the GM diet say it works because many of the foods included in the diet are low in calories, such as fruits and vegetables.
In a 2015 study of more than 133,000 participants, people with the highest intake of fruits and non-starchy vegetables had the lowest risk of weight change over a four-year period ( 1 ).