The Stillman diet is a high-protein diet regime that permits adherents to eat an unlimited amount of lean meat, sea food, poultry, eggs and low-fat cheeses. Meals should be small and taken six times a day. The diet suggests bread, vegetables, fruit, sugar and alcohol should be struck off the dieter’s menu. As for liquids, at least eight glasses of water per day are recommended in order to rid the body of unwanted ketones. Coffee, tea and diet soda drinks are allowed on the diet and it is recommended that dieters top-up on vitamin supplements throughout the dieting process.

Doctor Irwin Maxwell Stillman (1896-1975) invented his Stillman diet in the 1960s. He had worked as a family doctor in Brooklyn for the most part of his career before he retired to Florida. His 45 years in practice and his experiences treating thousands of overweight and obese patients lead him to the understanding that a high-protein diet was the most effective way of losing weight. Moreover, his experience of fellow doctor Eugene Dubois’ diet plan added to his understanding of how digestion affects weight loss. That is to say, Dr Stillman understood that the body uses up 30% of all calories consumed in breaking down the less tractable food stuffs in the diet such as proteins. Therefore, raising the intake of proteins to levels around 90% would mean that the body’s metabolism would have to work much harder, a process that the Stillman diet terms the "melting out" of body fat.

Proponents of the Stillman diet suggest that dieters lose anywhere from 7 to 15 lbs (3-7 kg) during the first week of the diet and 5 lbs (2.2 kg) with each subsequent. This translates as 5% to 10% of a typical dieter’s body weight. For a dieter looking for a concise, easy to follow diet plan that is guaranteed to shed weight, the Stillman diet has obvious attractions. However, with the diet monopolized by protein intake, a Stillman dieter loses out on vital food stuffs. Though these can be replaced by vitamin supplements, should a dieter miss a supplement a deficiency is sure to follow as a consequence. Equally, the Stillman diet is wanting in fiber and adherents are likely to be constipated during their time on the regime.

With the success of his Stillman diet behind him, Doctor Stillman went on to devise a number of other diets throughout the 1970s and to write a book, The Doctor's Quick Weight Loss Diet (1967). A low-protein diet he called The Doctor's Inches Off Diet (1969) operated, surprisingly, on principles opposite to its antecedent and was a largely vegetarian, non-protein diet. His Quick Teen-Age Diet (1971) was a synthesis of his previous two diet regimes and prescribed for junior dieters a more balanced regime that added exercise to the healthful mix.