If following a very-low carb diet of less than 12% calories, then our system is in a primarily fat burning mode. This is also known as a ketogenic diet because the cells use ketones in place of glucose for energy. It has become popular in recent years due to its rapid weight loss benefits as well as certain improvements in overall energy levels and metabolic acceleration. But for practical purposes it is better to consider it as a process that occurs naturally when our bodies cannot find carbohydrates for energy. It is a backup system that functions on stored and dietary fats.
Our bodies normally contain a percentage of fat that starts at 20% for normal levels and can rise very high in case of obesity. This means about 15KG or more of fat. When multiplied by 9000 calories per KG equals about 145000 calories. Or the equivalent of about 45 days of energy needs at a 2500 calorie daily diet. This reduces the hunger signals that occur to encourage food intake in the case of a carbohydrate diet. It also makes sense because feeling hungry when food is not readily available in periods such as winter or drought would have adverse physiologically and psychologically effects.
When in a low-fat diet food intake will be processed for energy in an efficient manner because it is a singular process. Meaning that the energy needs are satisfied in a balanced manner and satiety happens as soon as the daily energy needs are met. Furthermore because fat is a dense calorie substance of 9 calories per gram it means that quantities are small and this helps reduce stomach size.
*Sources of information:
https://www.healthline.com/nutrition/10-benefits-of-low-carb-ketogenic-diets
https://my.clevelandclinic.org/health/articles/24003-ketosis
