The most potent natural stimulus to growth hormone secretion is fasting. In one study, over a five-day fasting period, growth hormone secretion more than doubled. During fasting, in addition to the usual early-morning spike of growth hormone (pulsatile), there is also regular secretion throughout the day (non-pulsatile). Both pulsatile and non-pulsatile release of growth hormone is increased during fasting. Interestingly, very low-calorie diets are not able to provoke the same growth hormone response.
