Our weight depends on a variety of factors, but one secret to healthy weight is found in awareness of the role the hormone insulin plays in fat storage.
It is wrongly assumed that consuming excessive calories is the root cause of obesity. However, a calorie of food energy has different metabolic fates depending upon the hormonal stimulation. That same calorie may be used to generate body heat or stored as body fat. It can also act as a signaling molecule to trigger a secondary response. The gut microbiome then interacts with the consumed molecules first and creates its own signaling to the human host and effects metabolic pathways, increasing or decreasing nutrient availability.
Obesity is a disease of failed energy partitioning, not one of total energy intake, and one of the primary drivers of this partitioning is the hormone insulin. Insulin is specifically a fat storage growth hormone. The mere presence of insulin causes an immediate metabolic shift from using fat as a fuel source, to storing circulating glucose to glycogen for a total of about 500 grams. Once the initial glycogen stores are full, then glucose is converted to fat storage, a nearly unlimited storage capacity.
Insulin is specifically a fat storage growth hormone. The higher your insulin and the more often your insulin spikes determines your fat storage, not the number of calories you eat.