In the early 2000’s, Drs. Mario Ciampolini and Riccardo Bianchi, two weight loss specialists, noticed that conventional weight loss diets often work in the short term, but not in the long term [1,2]. They observed that when people eat, it is sometimes not to stave off hunger, but because they are bored, they feel tired, they are addressing negative emotions, it is a habit, or that the food is linked with certain activities (e.g., watching a movie). The scientists surmised that when people are eating for so many reasons other than hunger, it is easy to overeat and gain weight. They hypothesized that if people were taught to distinguish bodily feelings of low energy from other physiological, emotional, or social states, they would gain more control of their eating and more easily lose weight and maintain a healthy weight.
In line with these ideas, Drs. Ciampolini and Bianchi developed hunger training [1]. Hunger is a perception, so when someone feels hungry, he or she is hungry, even if the body doesn’t need additional energy from food. Hunger training does two things: 1) it teaches people to be accurate at assessing their body’s energy levels, as assessed using blood glucose (also known as blood sugar), and 2) it teaches a person to experience hunger more specifically in response to low blood glucose as opposed to other reasons (e.g., boredom, tiredness, habit). During hunger training, which takes approximately 2 weeks, blood glucose is tested when an individual feels hungry. If it is below 4.55 mM (85 mg/dl), or an individualized threshold based on fasting blood glucose concentrations [2], the person can eat. Otherwise, the individual should refrain from eating and try again in an hour if the hunger remains. To put these blood glucose values in perspective, fasting blood sugar for a person without diabetes is approximately 3.9-5.5 mM (70-100 mg/dl) and can rise to 7.8 mM (140 mg/dl) or more after a meal.
The initial report by Ciampolini and Bianchi showed that most of their subjects could estimate their blood glucose to an accuracy of 4 mg/dl within 2 weeks of training [1]. In weeks 3-7, the participants applied their new skill of detecting low blood glucose and found decreases in both food consumption and feelings of hunger. In a follow-up study, Dr. Ciampolini and colleagues conducted a weight loss experiment [3]. After 7 weeks of hunger training and 3-months of practice, overweight participants lost an average of 5.8 kg (12.8 lb), which was significantly greater than that of the control group. Healthy weight participants who had low fasting blood glucose levels did not lose weight, but those that had relatively elevated pre-meal blood glucose levels did. These results suggest that hunger training can improve health, even for healthy-weight people. However, more research is needed to optimize the training protocol and better understand how hunger training affects caloric intake, dietary compliance, and the difficulty of maintaining a diet.
Hunger training is a part of the Quantified Self movement, which is the concept of continuously acquiring personal data throughout one’s everyday life such as food intake, heart rate, number of steps taken, quantity and quality of sleep, and many other activities. It has become possible with mobile technology and advanced (yet affordable) sensors. Wearable monitoring devices are drastically improving medical care and guiding behavior change [4], and hunger training is one way that modern technology may help people lose weight and achieve their personal fitness goals.