eli5: If a morbidly obese person stopped eating entirely, would they be thin by the time they starved to death?



eli5: If a morbidly obese person stopped eating entirely, would they be thin by the time they starved to death?

In: Biology

They wouldn’t survive long. While a body can survive off fat as caloric intake for the time being, without supplements, they won’t survive long. After the body uses its storage of sugar, the body can’t function. That’s why you feel so bad until you eat something after being super hungry. Following protein deficiency, muscles failing from lack of vitamins usually achieved from normal diet, a person would die no matter what their weight.

Edit: minerals as well like salt, potassium, etc.

It depends on exactly what they take inn. For example if they stop eating and drinking entirely then they will die from dehydration within just a few days. While they will be much thinner due to the dehydration they will still have most of their fat and therefore will not be considered thin. If you do allow them to drink water but without any sugar then they will be able to survive for weeks. But the problem is that the body needs certain vitamins and minerals. A few of these is stored in fat and will be released as the fat is burned but not all of them. So they will start to get vitamin and mineral deficiency diseases which will cause permanent damage and eventually kill them. So you need to take some multivitamin pills and such in addition to the water. The next issue is protein. The body is able to produce enough of some of the ammino acids used to make proteins and is also able to recycle ammino acid from dead cells. But this is not enough and without food there will be a lack of some ammino acids to produce new cells. This is not an uncommon problem in people who are on a strict diet. The body will have to prioritize which cells it will rebuild and which it will let die. So quite often the muscles will weaken a lot in this process. And because the body tends to conserve a lot of energy when not getting enough food there will be periods when the weight loss in muscles are greater then the weight loss in fat. So they might risk dying from a lack of protein to regenerate the cells before they have burned all their fat. The problem with adding protein to the diet is that protein can be used for energy as well. And the body will happily burn protein when it is low on energy even though it is also low on protein. So in general it is very tough to diet in a healthy way and it takes a long time.

Those type of crash diets would kill the person well before they starved to death, you want to cut the calorie intake, but not cut it out completely.

Look up Water Fasting. It is a thing and will not kill you if done with medical supervision.

No. Our bodies need more than just fat stores to keep living. That person should die of malnourishment before losing all their weight because they would be lacking all the micronutrients they need and other stuff.

Probably not. One of the reasons weight loss is so tricky are adipose cells. These are a type of fat cells that increase in number and size as we gain weight. These cells can never decrease in amount, only in size. Given that after a couple weeks without food(or even less depending on preexisting conditions) can kill, it’s unlikely that the adipose cells would have had time to shrink.

I am by no means an expert, that’s just my understanding of a single aspect of obesity.