I have noticed some similarities in how muscle cells and fat cells behave. Perhaps they can both be viewed as adaptive responses whereby morphological changes take place in cumlative fashion with the goal of leading to an enchanced ability to maintain homeostasis when being exposed to a certain stimulus.
With muscles, the stimulus is exercise and muscle fibres increase in size and number in order to reduce the overall level of fatigue that that particular exercise induced.
With obesity, that stimulus is hyperglycemia, hyperinsulinemia. With fat cells, they multiply in number ( Hyperplasia ) in order to increase the total surface area of insulin receptors that are
exposed to the bloodstream.
Everyone knows that post obese people have an extreme tendency for weight re-gain. This is attributed to the increased number of fat cells that were produced during obesity. I have seen a study on PubMed that showed that a fat cell's insulin sensivity was inversely related to its size. I.E., large full fat cells have low insulin sensitivity. And empty small fat cells have high insulin sensitivity.
When you loose weight, you dont change the number of fat cells you have, you change thier size only.
Likewise, this could predict that in muscle, after loosing strength and mass during a period of inactivity, you retain the number of new muscle fibres you made during hypertrophy, but what happened is that the number of myofibrials in each muscle fibre decreased.
As with the post obese, there is alot of anecdotal evidence floating around that it is easier to re-gain muscle mass once youve 'been' there before. This also fits in with the threshold theory of cellular behaviour, in that hypertrophy comes before hyperplasia.
That is, muscle fibres increase in myofibrials ( cross-sectional area ) before increasing in number. Indeed this is what happens with fat cells, they increase in size and reach a critical mass before new ones are made.
In the opposite direction, how does one loose weight? Well the way one looses muscle mass is by inactivity. They stop exposing thier muscles to the stimulus that made them become the size they did. This can be done by either reducing intensity of the exercise, reducing the frequency, or both.
With regards to obesity, low-carb diets can be seen as reducing the intensity of the stimulus ( reducing insulin spikes ), while intermittant fasting can be seen as reducing the frequency.
We know that its very easy to gain body fat by eating very often and if each of those meals spikes insulin high with lots of carbs. This happens even in the face of potentially low calories, I.E. low-fat.
This may suggest that in order to rapidly gain muscle mass we must apply the stimulus frequently with a certain minimum intensity, and that the calories of the exercise ( I.E. the number of sets we perform ) can thus be a secondary consideration. I intend to experiment with exercising once every 48 hours with 1 drop-set. As opposed to performing 4 sets of reps every 72-96 hours.
With fat mass, like muscle mass, if we want to loose it, we need to stop sending it the stimulus that made it that way. Ketogenic diet combined with intermittant fasting. However I think that carb re-feeds will still be helpful because they help boost leptin and change the critera for homeostasis adapation on a ketogenic diet will incude, I.E. the famous weight loss plateau.