No and yes. Let’s see why.
Fat represents the accumulation of calories as a result of eating more than required for one’s daily living needs. When one eats too much, the unused calories are stored in fat because we (as a species) have a thrifty metabolism (not every animals on Earth are as thrifty) : what isn’t used for our daily living is stored for later use. If that later use never happens, but one continues to over eat, then one can accumulate an impressive amount of fat. The sad part is that our metabolic thriftiness is apparently never-ending : our body is not programmed to stop accumulating when we have “enough energy” set aside. To make matter worse for some, men and women of certain descent (notably Amerindians and South Americans) have an even thriftier metabolism, which translates in our modern world as an even more marked tendency to gain weight.
Women tend to gain weight more easily then men because of estrogens. In a world of famines, this was a good thing because it allowed the mother to potentially survive longer to feed their progeny. In areas where abundance of food is the norm, this results in a tendency for women to gain weight easily.
Men have testosterone : a pro-metabolic hormone. Testosterone increases muscle mass, heart rate and energy expenditure over all. This explains why men tend to eat a lot and not gain that much weight, especially in their younger years. As they get older, however, testosterone levels tend to drop slightly over time : a male in his early 20s will burn 200 calories more for his daily routine than a man in his early 40s doing the same things. Hence the “beer belly” of men in their forties : they kept the same eating habits even though they did not need as much… and fat accumulated over time.
For men, this accumulated fat has another unexpected consequence : fat tissues contain an aromatase enzyme that converts testosterone into estrogen. This conversion rate gets more important as fat is accumulated, to a point where some fat men will have as much estrogen in their blood as women of the same age ! This high level of estrogen as a result of accumulated body fat will have many consequences :
- loosing weight will become much harder because estrogen favours body fat as we have seen above
- energy levels will go down as the testosterone level drops, the resulting apathy will make losing weight harder also
- sex drive will drop as testosterone level drops too
- body hair will become thiner
- gynecomastia (growing of breasts) may happen. Male breasts will never become very big, but they can grow to the size of an early teen girl’s size. One has to remember that we have everything in our bodies to be both male and female, but our hormones favoured certain organs instead of others (nutshell explanation). So when the breasts of a male are exposed to higher lever of estrogen, they may develop enough to be perceptible.
This being said, even in women, breasts are mainly made of fat. This particular area of the body is used very early to store excess energy (in other words : fat). So fat men will have rounder, bigger breasts because of fat accumulation much earlier than because of gynecomastia.
So, your question were :
a) Is a fatty man’s chest the same as the chest of a man suffering from gynecomastia ?
And the answer is
- mostly no as breast are used very early as fat stores, so fat men will have big breasts as a matter of course because of them being fat in the first place
- and a little bit of yes, considering that the accumulation of fat will flip the balance in favour of estrogen at some point, leading to development of breast tissue.
b) Is the fat tissue in fat chests the same as breast tissue?
Yes, because a man’s breast is just an underdeveloped female breast.
While gynecomastia cannot be reversed, losing weight will lower estrogen level leading to an increased level of energy, sex drive, and general feeling of well being… as well as a disappearance of 99 % of man-boobs’ size.