How Long Can an Obese Person Survive Without Food?

How Long Until an Obese Person Starves?

Most people who are confronted with a survival situation where food is scarce will inevitably wonder how long they can survive without food. But what if you have a few extra pounds on you? Does this mean you’ll last longer?

Well, if you do happen to be seriously overweight, or even obese, you may be surprised how long you can last before starvation gets the best of you. Especially if you have a few extra multi-vitamins laying around you can utilize.

How Long Can an Average Person Survive Without Food?

The average person can survive approximately 21 days without food before succumbing to starvation.

The general rule of thumb is that a person can survive 3 days without water and 3 weeks without food. However, it really depends on a list of factors unique to each individual. Your starting weight, for example, will play a part in your survival without food. The environment, your overall health, and even the quality of the food you consumed before all hell broke loose can all play a role as well. Surprisingly, the biggest factor has to do with hydration.

How Long Can an Obese Person Survive without Food?

In general, a person can survive up to 110 additional days for every 50 pounds of excess body fat depending on exertion levels, hydration, overall health, and other factors specific to that individual. In one documented case, a 456 pound man survived 382 days without food, consuming only occasional vitamin supplements.

During the starvation process, the body will burn fat for energy to keep the body alive. Not surprisingly, a serious overweight or obese person generally has significant more fat cells than an average person. For this reason, this stage of starvation can take significantly longer, allowing the overweight person to live much longer than the average person. However, there are still many other factors including the amount of excess fat, that contribute to determining how long an obese person will survive.

The Starvation Process

A lot happens when your body is deprived of food. I want to go over the physiological process of starvation so you can avoid that fate yourself. It starts out the same for everyone, but there’s a point in this process where obese people can really shine.

  • 12 hours after your last meal, you may experience mild stomach cramps. It’s just the familiar gurgle of an empty belly. At this point, it’s only about as bad as waking up from a long night of rest and being hungry. You’ll probably start thinking about food quite a bit, but nothing too dramatic.
  • 24 hours post-meal, your stomach cramps will have increased significantly. You may begin to burp, feel nauseous, and obsessively think about food. Your mental acuity will likely decrease slightly due to distraction, but you will still be able to get important tasks done. Your blood sugar may be low and you’re probably going to feel cranky. It’s not fun, but there isn’t a reason to panic just yet.
  • 48 hours after your last meal, your body will have burnt off the last of your glycogen stores from your liver and muscles. You will likely feel fatigued, agitated, and unable to focus on complex tasks. You may feel shaky and unstable. This is the transition period, a signal for your body to do something drastic.
  • Once stored glycogen is depleted, your body will begin to break down fat into ketones for fuel.  The rate of fat usage varies from person to person, but this stage can last for months. This is the point where being obese, or even just a bit overweight, can give you a significant advantage over a thin person.
  • You can survive at this stage for quite some time if you have large fat stores. However, your brain cells and red blood cells can’t use ketones, so your body will also break down muscle at this point.
  • Once the fat is gone, the only thing left to break down is muscle. This is the point where things get dire. Muscle tone will drastically decrease and you will have lost significant weight by now.
  • After a while, cells will begin to die from lack of proper nutrients. Which ones go first and how quickly will depend on your personal body composition, but suffice it to say, accelerated cell death is bad news.
  • Potassium levels will plummet, causing muscle spasms and weakness.
  • As more cells die, your immune system will become compromised, setting you up for infections and illnesses.
  • Electrolytes will become unbalanced, which makes it harder for oxygen to reach your organs.
  • Once severe starvation sets in—after about 40 to 50% of your body weight is lost—your muscles will begin to atrophy.
  • Abdominal bloat, flaky skin, dehydration, hair color changes, and paralysis signal the beginning of the end. Intervention at this stage is often unsuccessful. By this point, the immune system is all but destroyed and the ability to consume enough food to nurture your ravaged body is gone.

Psychological Effects of Starvation

I can’t talk about starvation without also exploring the psychological ramifications. Mental health plays a huge role in physical well-being. Survival is already stressful on your body, but emotional and mental problems can make matters much worse when there’s a real threat of starvation. Some of the possible effects are:

  • Depression
  • Obsessive thoughts of food
  • Irritability
  • Apathy
  • Guilt
  • Confusion
  • Elation and vindication (You survived while the skinny people who used to torment you are all dead)
A far man eating a burger and fries so he can survive longer without starving.
A little extra body fat could save your life.

How Overweight People Have an Advantage

So,  we know that Mr. Gymrat can make it a few weeks without his kale and kombucha. Not too bad. But in general, seriously overweight or obese people can likely do far better.

If you came into the apocalypse with a spare tire, a set of love handles, or a full keg around your middle, consider yourself lucky. Science says obesity gives us an advantage over the thin or super-fit when it comes to starvation. For proof, look at the popular ketogenic diet. The keto diet forces your body to burn fat instead of carbohydrates.

So what do obese people have that thin people don’t? Fat!

Because everyone’s fat to muscle ratio is different (and everyone burns fat at different rates), there isn’t a hard and fast rule here. But if you look at your personal stats, you can make some estimates. When your body switches to burning fat for fuel, it stands to reason that more fat equals a longer survival period before total starvation. So how did we get the estimate that a person can survive up to 110-days for every 50 pounds of excess fat on their body?

Here’s my math: One pound of body fat equates to about 3,500 calories. If you burn 1,500 calories a day just sitting around, that’s approximately 2.3 days living off of one pound of fat. If you happen to have 50 pounds of extra fat, that comes out to over 110 days. There’s more to it, of course, but this is a good place to get you started.

Case Studies: Surviving Starvation

Hunger strikes are not all that uncommon, and they provide us with great insight into what the human body is capable of. The case of Mahatma Gandhi was well documented. He was in his 70s when he survived 21 days of starvation. Cesar Chavez went for 36 days without food, while Solange Fernex went for 40 days. You can read more details on these incidents here.

Those aren’t even the longest, but you and I won’t be staging hunger strikes after the apocalypse, so what about involuntary starvation?

For a healthy adult, salvation could be as simple as finding one morsel of food per day and a few swallows of water. Take Rita Chretien, for example. She survived an impressive 48 days in her vehicle eating a very small amount of trail mix and drinking water from a nearby stream. She ended up losing about 30 pounds through her ordeal, but she survived.

All of these people survived nearly starving in different situations. But there is one important similarity. Each of these stories specifically mentions access to clean water. Dehydration can kill you in under a week, even if you have plenty of food and medical care. If you have to choose between hunting for food or finding water, look for water.

What’s the Longest a Person has Survived Without Food?

This article from NCBI explores the case of a man who survived a whopping 382 days without food. The man in the study weighed 456 pounds at the start of the fast and got down to 180 pounds by the end. That means he lost a total of 276 pounds throughout the ordeal! Doctors monitored him and gave him vitamin supplements, but that’s it.

Not surprisingly, the patient went 37 – 48 days between defecations. The man suffered no lasting ill-effects from his ordeal. In fact, five years after undertaking the fast, he still weighs around 196 pounds.

Many bug out bags and prepper stashes include multivitamins and other supplements. There’s a good reason for this, and it’s not just to boost your post-disaster nutrition. With proper hydration and a decent store of body fat, long term survival on just supplements alone is possible.

Having access to multivitamins and other supplements will greatly increase your survival odds when you can’t find food. A nice bonus is that supplements are small, lightweight, and easy to carry around while you search for food.

Note: All numbers are rough approximations and should not be relied upon. Consult with a doctor before attempting any type of fasting.


How to Calculate How Long You May Be Able to Survive

With an estimate of how many pounds of extra fat you are carrying around with you, and the total number of calories you expend in a day, it’s possible to calculate out how many days you can survive without food. Of course this number is an approximation at best and should not be relied upon. Always consult with a doctor first.

Step 1: Check your TDEE (Total Daily Energy Expenditure) using this website. This website will tell you how many calories your body burns per day just staying alive.

Step 2: Take the estimated amount of body fat you have and multiply it by 1,500. This number will be an approximation of the number of extra calories your body has in reserves, in the form of fat.

Step 3: Take the number of calories you have stored as fat and divide it by your TDEE number you got in step 1. This will be the approximate number of days of survival your extra body fat will buy you.

Gaining Weight as a Survival Strategy

I’m not going to suggest preppers and survivalists start packing on hundreds of extra pounds while waiting for the world to end, but I can’t deny the facts. As long as you can still get up, move around, build your shelter, and hunt for food, the extra weight from a few cheeseburgers today won’t be a bad thing when you can’t find food in a survival situation. Wait, did I just provide you with the perfect excuse to go eat a cheeseburger? Maybe.

Having higher body fat isn’t socially acceptable in our current fitness-obsessed society. However, when it comes down to survival, those extra jiggly bits can help. Your extra fat can stabilize your metabolism and sustain you until you can secure your next meal. A rail-thin person with very little fat and weak muscles isn’t going to last as long as a beefy lumberjack with a big belly.

My best advice for those considering gaining weight for survival purposes is to do so slowly and with quality foods in mind.

  • Eat fresh fruits, vegetables, and lean meats.
  • Have that cheeseburger and fries no more than once a week.
  • Don’t neglect your fitness while aiming to put on weight. The last thing you need to do is get so big so fast that you can’t perform basic daily functions.
  • Build muscle too. Your body will have to break down muscles to feed your brain when going a long time without food, even if you have extra fat.
  • While you’re gaining slow, steady weight, also work on your flexibility and endurance. That will help to get you to your bug out location, carry your BOB, and build your shelter without having a heart attack.


I think it’s safe to say that being overweight when the world ends or you get lost in the woods is more likely to work in your favor than being super thin with an extremely low percentage of body fat. This doesn’t mean we should all go out and purposefully become morbidly obese on the off chance disaster will strike. However, I feel like having a few extra pounds isn’t necessarily a bad thing, especially when you’re otherwise healthy. It just might give us a leg up when it comes time to survive.

So did I just make you want to run out and eat a burger? What are your thoughts on starvation? Share in the comments below!

John Walter

John Walter is an emergency preparedness consultant with eight years of experience and training in related fields. He is a passionate prepper living in the Sacramento area of California.

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