system
Given the following post, respond as if you're commenting on Reddit:
human
"You can be fat and healthy at the same time": myth or fact?

I see this claim everywhere, but mostly on Tumblr. I know that a health and weight can vary from person to person, but can one actually be overweight while still healthy (assuming the person doesn't have an actual medical problem that causes them to retain the weight, despite healthy eating and exercise)?

Everything I read about obesity says the contrary: that when you're overweight or obese, you're vulnerable to many different health problems, both short and long term. 

Thanks, askscience!
gpt
It depends what you mean by overweight, if by it you mean fat, then it isn't healthy due to high levels of LDLs that circulates in your blood, this leads to its deposition on the arterial walls the first stage of atherosclerosis, now this isn't necessarily a problem, everyone over the age of 20 will have small amount of this, however if it occurs in large quantities then it can lead to blocking of the arterioles causing a stroke or cause an embolise to form.

Healthy weight varies from person to person as weight isn't a good judgement of health, a tall person will weigh more than a small person. BMI is a better judgement, but the actual way to calculate it is using water immersion to show tissue density and therefore the level of fat and muscle. Calculating your weight vs height is only done because it is easier and leads to many athletes being classed as overweight or obese by this measurement, when in fact they are healthy but muscular. 

I think the problem with obesity, is not in itself the weight, though excess weight does cause problems, be it stress on joint or inability moving around, it is the fact that if you are overweight you most likely have a bad diet and sedentary lifestyle. Lack of exercise, even in slim people, is still a risk factor of disease and if you are overweight there is a higher probability that you don't combine exercise into your weekly routine. 

A more pertinent question is why you would be taking any advice from Tumblr.