The trick here is not only to avoid all obvious sources of carbohydrate (sweets, bread, spaghetti, rice, potatoes), but also to be careful with your protein intake. If you eat large amounts of meat, eggs and the like, the excess protein will be converted into glucose in your body. Large amounts of protein can also raise your insulin levels somewhat. This compromises optimal ketosis.
All of this is important to understand because while the basics of changing your body composition are simple –energy balance– each person’s personal psychology and physiology will differ. Someone who’s never exercised before and has a lot of fat to lose will have different physiological and psychological requirements than someone who stopped training for a while and gained some body fat in the interim; conversely, a lean beginner is going to be in a different place than an overweight beginner.
The prevailing formula for a long time on how much fat you’re going to burn was calories in minus calories out, based on your basal metabolic rate (BMR) and exercise efforts, explains strength and performance specialist Joel Seedman, Ph.D., owner of Advanced Human Performance in Atlanta. But with all the different biochemical reactions in the body, hormonal response, and endocrine function, there are an infinite number of factors that can affect how your body is storing and breaking down calories.