A person will typically start a “reverse diet” after a period of prolonged calorie restriction to gradually increase their metabolic rate and to limit the amount of body fat they gain throughout the process. The reverse diet emerged from the principle that when your body becomes accustomed to higher calories, it will become less efficient with the calories you consume and vice versa. Your body is smart, and it is constantly adapting to its environment. Your body will burn fewer calories when it encounters a famine (calorie deficit), and it will burn more calories when it is consistently fed. However, a reverse diet is most effective when it is paired with a good resistance training program. This kind of training stimulus sends a signal to the body to partition more of its calories to your muscle mass rather than to your fat mass, thus reducing the amount of fat you gain while you increase your caloric intake in a reverse diet. As you follow a reverse diet and lift weights, you can increase your lean body mass while decreasing your fat mass and this increase in muscle mass and in training capacity also speeds up your metabolic rate. Thus, both lifestyle interventions work well together to achieve the goal outcome: to increase your metabolic rate while preventing excessive fat gain.
So how do you start a reverse diet? First, you will need to know what your maintenance calories are. It is best to avoid using online BMR (basal metabolic rate) calculators or generally accepted BMR formulas (e.g., Harris-Benedict equation) to determine your maintenance calories as both methods can be terribly inaccurate. For example, my maintenance calories are around 2,700 calories per day, but the online calculators/formulas say that my maintenance calories are closer to 1,500 calories per day. To find your maintenance calories you should track and average your daily calorie intake for two weeks. If your weight remains stable within a 2.5% weight fluctuation day-to-day, you can begin by adding 50 to 100 calories every 1–3 weeks depending on how much your weight changes each week. If your maintenance calories are very low (e.g., <1,500 calories), you will want to be more conservative with the frequency and number of calories you increase during the earlier weeks of your reverse diet to avoid excessive fat gain.
If you have healthy sex hormone levels and you want to start a reverse diet, you first should increase your protein intake if it is below the optimal recommendations for individuals following a resistance training program (~1g protein per pound of lean body mass). If your protein intake is sufficient, you can add either more carbohydrates to help fuel your workouts and aid your recovery, or you can add more fats to help reduce your hunger. If you do not have reasonably healthy sex hormone levels as a result of prolonged calorie restriction, a reverse diet may not be the best approach for you. It would likely be more beneficial to rapidly increase your calorie intake and to accept some fat gain as a part of the process. Your body will shut down its sex hormone production when its fat stores are too low, so gaining some fat can be necessary to upregulate your body’s sex hormone production; weight gain is not always a bad thing.
There is the common misconception that a person will not gain weight while following a reverse diet. This confusion stems from the “avoiding excess fat gain” aspect of the reverse diet’s premise, but weight gain is inevitable to some degree in a reverse diet. Your weight will usually first increase when you notably increase your food volume and carbohydrate intake. This adds the weight of the food itself, and your body will hold more water weight as a result of the food. As a person increases their carbohydrate intake, they increase the amount of glycogen they can store in their body. For every gram of glycogen your body stores, your body will store a few grams of water with it. This can add pounds to the scale if you have significantly increased your carbohydrate intake. Further, as you reverse diet while following a resistance training program, you may increase your muscle mass and its ability to store more glycogen, which will also add more weight to the scale. This may sound discouraging, but a person can still get leaner as they gain weight. As you increase your muscle mass and gain weight, your body fat percentage can decrease if you are primarily gaining muscle mass. That being said, the reverse diet offers a nuanced perspective towards weight gain and a viable approach for increasing your metabolic rate, while simultaneously maintaining or improving your body composition.
