That's an error in reasoning, since you do not experience the effort your friend does. I think this is worth dilating on...
The mistake is using a "between" comparison instead of a "within" comparison. If I and a horse set out to walk a mile, the horse can rightly say that it took more effort (more calories burned) for the horse than me. In fact, if we limit how many calories are burned, the horse might have to stop after a half mile. It could rightly say (by using a "between" comparison) that it takes less effort to walk a mile (when I do it) than walking half a mile (when the horse does it). But obesity and effort should properly be measured as a "within" - on an individual basis, comparing me to me.
Uuummm....WHAT!?
Marplots, this was the original argument:
"It is much easier to lose weight, than to gain weight."
That is a VERY broad-brush argument, and far too simplistic in terms of biology! In some instances, that may be true. (My friend.) In other instances, that is completely false. (Me.)
The entire point of comparing two different human bodies, is to show the extreme variability of two different human beings and how the body functions from one individual to another. I don't have to experience what my friend does. It is a fact: He is thin even though he has a normally terrible diet (one high in fats). I am slightly overweight, even though I have a very good diet. The difference being, the metabolic rate of his body compared to mine. I have to work a hell of a lot harder to keep from becoming overtly fat than he does. He has to work really hard at maintaining a healthy amount of fat without wasting away.
This directly and immediately disproves the notion that "gaining weight is harder than losing weight."
The point stands. Since I'm using animals (to avoid the "fat shaming" trope), I present the bear. He's out consuming as much as possible during the spring and summer, expending energy far above his metabolic minimum. But because he is consuming many more calories than he is using, he gains a tremendous amount of weight.
That same bear then goes into hibernation. Now, he's at a metabolic minimum (his "zero" point) and making no effort. He loses weight. Why? Because, even though he is making no effort, his metabolic minimum still burns calories.
This in absolutely no way proves anything about your idea that "gaining weight is harder than losing weight." Forget about stupid animals. You are just confusing your arguments. Stick with the person in a coma. (Cannot believe I am doing this. UGH!)
A person in a coma loses weight while he sits in bed. The person in a coma has no way of responding to external, or internal stimuli. The person in a coma is, for all intents and purposes, at the mercy of his/her own body, and the external environment. Doctors, for instance, feed a coma patient a very specific combination of fluids though an IV to keep that person from starving to death. (The very act of breathing...converting oxygen to carbon dioxide....necessarily requires energy. If you are alive, in other words, no matter what, you are consuming energy.)
So yes. You are correct. A person in a coma does lose weight. Simply because that person cannot feed themselves, and their body must rely on what the doctors give them to consume. Not to mention, their body chemistry is completely out of whack, simply because their brain is not functioning normally. (You do know that the brain is a huge contributor of balancing certain chemicals, and the consumption and distribution of energy, right? When the brain is nearly out of commission, that throws your entire biological system totally out of whack! Again, comparing a coma patient to a fat person who is 100% conscious is comparing apples to orange trees!)
Now, your point that you are TRYING to make, is that it is easier to not eat than to eat. You are exactly wrong on that point! It is INCREDIBLY difficult to keep yourself from eating if you are hungry! Just ask anyone who has ever attempted a food strike. Or at least, try it yourself. Go 5 or 6 days without eating a solitary thing. I guarantee you would cave in about 2 days.
We are a product of evolution. Evolution that stretches back nearly 4 billion years. Living things have a strong desire to live. And to live, they must consume. Therefore, living organisms have a very strong desire to consume. That is something which is not very easily overcome.
In our modern world, it is a hell of a lot easier to just stop at McDonald's and grab a burgher real quick, than it is to go to the supermarket, walk through the store, look at all the food labels, go to the counter, pay for it, go home, and prepare a meal. One requires actively, and consciously making informed decisions arrived at by more work of counting calories and carbohydrates.
Now tell me: How in the world is it "easier" to go to the supermarket, read all the labels, count all of the calories, plan out your meals, then cook your meals....than it is to just run right over to McDonald's and grab a burger, fries, and a Coke?
Not to mention, if one wanted to work off your meal: Working off a vegetable salad that you prepared yourself, is a HELL of a lot easier than working off an 800 calorie meal full of fat, sodium, and sugar from McDonald's.
Now let's get even less extreme:
For myself, I do shop at the grocery store. (Lord knows, I couldn't even afford to eat at McDonald's everyday anyway. They charge nearly $8 for a friggin meal! That, and I have acid reflux. Bad foods literally make me sick. I cannot eat it, same as someone who is lactose intolerant cannot drink milk.)
For the most part, I stick to the outer edges of the store. I only venture down the aisles if I need something specific, like oil or vinegar, or herbs and spices. Granted, I do eat my fair share of red meat. But only usually about 2 or 3 times a month. I do workout on a regular basis. I still have a small gut on me that I will never be able to lose without even more extreme measures. Losing weight for me is extremely difficult, and very time-consuming.
I have a low metabolism.