Quick summary:
The size of the fat cell; formally called the adipocyte, determines how sensitive you are to insulin. When fat-cells (adipocytes) are small, the body is obligated to increase insulin-sensitivity to fill up those fat-cells.
The size of the adipocyte determines the type of hormones the adipocyte secretes; some hormones like adiponectin are beneficial while some, like resistin, are not.
The storage of dietary-fat inside fat-cells is healthy fat metabolism. When you eat fatty foods, the best place for that fat to end up is inside the fat-cells. However, the more fat that gets stored within the adipocytes causes them to enlarge. And like said before, when fat-cells enlarge they began to malfunction; they begin to secrete inflammatory hormones, they begin to suck up steroids and most importantly they begin to lose their sensitivity to insulin.
Now insulin has some very important roles in fat-cell metabolism. In healthy people, insulin is supposed to store dietary-fat in the adipocytes and inhibit the adipocytes from undergoing a process called: lipolysis.
This is crucial to understand, because when the fat-cells enlarge they are less able to store dietary-fat and become less sensitive to the inhibitory effects of insulin on the lipolysis process.
When the fat-cells become too large, the body purposely induces insulin-resistance within the fat-cells in order to shrink them and eventually restore insulin-sensitivity. When the fat-cells become insulin-resistant, they do begin to shrink but they release a huge flux of free-fatty-acids (FFA’s) —or commonly called non-esterfied-fatty-acids (NEFA’s)—into the circulation as a consequence, these FFA’s eventually end up accumulating inside the mitochondria of cells in very important organs (like the muscles, pancreas, heart, kidneys, brain, liver, veins, etc) and causes malfunction, inflammation and oxidative-stress within the cells of these organs, causing them to undergo a process called lipoapoptosis. The accumulation of FFA’s in cells also reduces the storage of glucose and amino-acids.
Eating in a way (and practicing techniques) that keep fat-cells small will ensure that you will keep optimal insulin-sensitivity as you age.
Exercise causes acute lipolysis and exports FFA’s to the muscle for oxidation. This in turn will actually increase insulin-sensitivity since the fatty-acids being exported from the adipoctye will actually be oxidize during exercise.
Fasting is another good way of shrinking you fat cells, as it once again it causes the body the shift into a fat-burning mode. Fasting for a day can burn about half a pound of fatty-acids.
Lipolysis is fine as long as you burn more fat than you ingest. Certain foods are notorious for causing fat-cell hypertrophy.
The first foods that need mentioning are saturated-fats found in butter, milk, cheese, meats, eggs, etc. Saturated-fat is very easily stored within the adipocytes, causing them to enlarge.
Vegetable-oils are the most fattening food on the planet. Vegetable-oil (of any kind) is pure fat and all of it gets deposited right into the fat-cells, causing them to enlarge.
Next are nuts, seeds and avocadoes. Many health conscious people eat nuts and avocadoes shamelessly, however this fat is going to be stored… besides, most of the fat in nuts and avocadoes is omega-6, which modern humans have way too much within our bodies already.
Last is fructose. Fructose converts into fat, which in turn can enlarge fat-cells… but by removing the major sources of premade-fat (animal-fats, oils, and nuts) fructose by itself is not as likely to induce fat-cell hypertrophy (when combined with a low-fat/high-fiber, starch based diet).
In order to shrink your fat cells, a protocol of temporarily fasting (24 hours per week) ,combined with daily exercise, combined with a diet of grains, beans, vegetables, stews and soups will do the trick. Once your fat-cells shrink, you will begin to regain your metabolic-health and be able to better store nutrients within the body.