According to the Mayo Clinic calculations, losing 5 pounds of fat requires a calorie deficit of 17,500 calories. To reach that level in two weeks, dieters need to achieve an average calorie deficit of 1,250 calories per day through either reduced food intake or increased exercise. As the Mayo Clinic explains, a calorie deficit is defined as the difference between calories consumed and calories burned.
WebMD advises against cutting calorie intake any lower than 1,050 to 1,200 calories a day. Cutting calorie levels too low can be unhealthy. Additionally, lowering calorie intake can slow the metabolism and actually hinder weight loss. WebMD also recommends reducing salt and starch intake. Both salt and starch increase water retention in the body, so eliminating those items can lead to losses of water weight.
For rapid weight loss, WebMD recommends avoiding sugars and the fats from meat and dairy in favor of vegetables, fruits, fish and lean meats. The Mayo Clinic suggests eating smaller portions, eliminating high-calorie foods or substituting them with lower-calorie alternatives. Both WebMD and the Mayo Clinic recommend keeping a food journal or diary to keep track of calorie intake and exercise as well as to identify behaviors that lead to increased calorie consumption. WebMD suggests dieters aim to exercise at least one hour each day.