Unintentional weight loss can occur because of an inadequately nutritious diet relative to a person's energy needs (generally called malnutrition). Disease processes, changes in metabolism, hormonal changes, medications or other treatments, disease- or treatment-related dietary changes, or reduced appetite associated with a disease or treatment can also cause unintentional weight loss. Poor nutrient utilization can lead to weight loss, and can be caused by fistulae in the gastrointestinal tract, diarrhea, drug-nutrient interaction, enzyme depletion and muscle atrophy.
The plan is based on the theory that eating carbohydrates creates a production of insulin, a hormone secreted from the pancreas, leading to increased weight gain and hunger. When converting to this approach, the plan holds that dieters will experience a reduced appetite, and their bodies will use stored fat for energy versus burning glucose from carbohydrate digestion. Burning fat for energy will supposedly lead to weight loss.