What Happens If You Don’t Eat For A Week?

What Happens If You Don't Eat For A Week? 1

Fasting is the new fad, and if you check numerous forums, where people talk about their fasting experience you’ll find, it has helped a lot of people lose weight.

You’ll see, people talking about how they tried all kinds of diets. low carb, the keto diet, low fat, reduced sugar, all kinds. But for some folks, none of those worked for them. Then they fasted, and the weight came off.

On top of that, they talk about mental clarity, feeling light on their feet, more agile. You can watch David Sinclair, a Professor in the Department of Genetics at Harvard Medical School, telling people they should skip meals, something in the past that was seen as an unhealthy way to live.

So what happens when you fast, either doing the short intermittent fasts or the grueling 5-day fasts? Let’s find out.

Harvard University is where we decided to go to find out about intermittent fasting, only because we believe we can trust the school’s research over some other more dubious health guru websites. Scientists at Harvard, including David Sinclair who we just mentioned, have done all kinds of tests on rats to see what makes them healthier or unhealthier.

When it comes to fasting, the rats came out looking pretty good. The results were often the same with any of the rats on a fast, it would lose weight, and its blood pressure, cholesterol, and blood sugars would often improve.

The U.S. National Institutes of Health agreed that when rats fasted there were health benefits, including a more efficient energy metabolism. That’s rats, though, not humans. So, what scientists then had to find out is would humans get the same benefits? Should we give up three square meals a day, or lots of small meals, and just deprive ourselves of food now and again?

What Happens If You Don't Eat For A Week? 2

Let’s have a look at what happens to the body when we fast. The experts tell us that when we don’t feed ourselves for somewhere between 12 and 16 hours our glycogen stores in our liver become depleted. The body then switches from using sugar as a source of energy to using fat. If you did a lot of exercise this can also happen. This metabolic state that happens during this time we call ketosis, and this brings about changes in the body.

Most of us don’t reach this state because we have grown up being told to eat when hungry, don’t go to school on an empty stomach, or we just put sugar in that morning coffee at the office.

Fasting means trying to avoid calorie intake, although some say a few calories might still keep your body in the fasting state. That’s debatable, as some say only have water or tea. As we said, some leading researchers around the world did lots of tests on rats, allowing some to eat what they wanted and others were only given food now and again.

This is the conclusion we found in one paper that was published by the National Institutes of Aging.

Emerging evidence suggests that intermittent dietary energy restriction might improve overall health and reduce risk factors for diabetes and cardiovascular disease in humans. Our new findings in laboratory animals provide evidence that similar intermittent eating patterns can enhance the beneficial effects of aerobic exercise on endurance performance.

You can read a lot of books on why our obesity crisis happened and the long and short of it all is many people are too sedentary, or just eat way too much and way too much sugary processed food.

intermittent fasting

It won’t surprise you that the book “The Obesity Code” tells people they shouldn’t constantly be snacking and they should try and eat healthy foods, more veggies, fruits, healthy proteins, and less refined grains, processed foods and sugar. It’s no surprise that some of the fattest countries in the world have a snacking culture and a fast-food culture.

Still, some people do eat quite well and still can’t seem to lose weight. It’s as if the body has a certain calibration and wants to stay at a particular weight. That’s where fasting has helped people. It’s worked where diets have failed. You see, there is some evidence that even when we restrict our bodies of calories the body thinks oh God, I am starving, and so slows down and takes what it can from the few calories you put in.


Even if you are a big person, if you reduce calories you might not lose weight because your body goes into survival mode. It slows down its metabolism. If you watch enough Joe Rogan you’ll know this is an ongoing argument, but what most people do agree on is that fasting seems to work for most people. But if you look at human studies which had some people on a plant-based healthy diet and some other doing one day fasts, the results weren’t much different. Some people lost weight, others weren’t affected much at all.

Then again, there is lots of evidence out there from people who tried fasting and the results for most people were positive. But we’ll get around to that later. Researchers from the University of Alabama were interested to see if fasting might help people with prediabetes, meaning they were on their way to getting full-blown diabetes. It’s well known that if you eat a ton of food before you sleep it can increase your chances of getting diabetes.

We don’t need to tell you that if you are very obese because your fingers are hardly ever doing anything other than putting chips, cookies, all kinds of processed junk into your mouth, you are at risk of getting diabetes. The proof is in the pudding, and America has a big pile of evidence. In 2018 the U.S. Centers for Disease Control and Prevention told us that one in seven Americans has diabetes, and while lifestyle is not to blame for around 5 percent of cases, the vast majority of the remaining 95 percent have diabetes because of a poor diet and resulting obesity.

What Happens If You Don't Eat For A Week? 3

So, can fasting help? Well, in one study the researchers put prediabetics on a plan called “early time-restricted feeding.” This meant some participants could only eat from 7 am until 3 pm and nothing else after or before. The other group could eat between 7 am and 7 pm, a kind of normal timeframe for most people. Both groups didn’t gain weight or lose weight, but those in the 7-3 timeframe showed a drop in insulin levels.

They also showed a lower blood pressure, and another important factor was they just got used to it and showed a decrease in appetite. There is no doubt that this kind of intermittent fasting has worked for a lot of people, but most researchers do say if you do it also try and have a healthy diet and a healthy lifestyle.

Dieting may also help, but the fact is some people find it easier to just skip meals. Sometimes it’s hard to find healthy food and sometimes it takes too much time to cook, so fasting is a good option if you want to try and lose weight without much planning or effort.

What about fasting not just for a certain part of the day, but missing an entire day’s food? The American Journal of Clinical Nutrition published a study from independent researchers who took a bunch of participants and put them on this one day a week fast for five weeks.

It concluded that indeed people lost weight, but they were also hungry during that fasting day. It said perhaps adding one healthy meal on a fasting day would be better. That’s why you’ll hear a lot about 16-hour fasts, 18 hours fasts, 20 hours fasts. Maybe start with the 16 hour fast and build up to 24 hours.

All over the web, there is scientific and anecdotal evidence that fasting can help reduce a person’s weight and also help people with type 2 diabetes. Some evidence also points to fasting increasing something called the BDNF protein in the brain, which is why some people claim they have enhanced mental clarity when fasting.

Others say that giving the body a break from food can help reduce pain and inflammation and also help repair cells. Some studies have concluded that chronic pain can be eased if fasting is done in tandem with a vegetarian diet, while there is some quite strong evidence that tells us fasting might help with other chronic degenerative and inflammatory diseases.

We found one paper in which scientists wrote that fasting might help regenerate stem cells and so could have a positive effect on cancer patients. Studies on animals show that fasting might even reduce the chances of getting Alzheimer’s disease or heart problems, but so far these studies have been done on animals so right now we should say it’s only a possibility it could do the same for humans.

We should say, however, that doctors don’t recommend pregnant women fast, nor malnourished people, nor people with a history of eating disorders, children, or women who are breastfeeding. It’s best to do it when you are an adult and you feel you need to lose some weight or lower your blood sugar. During your fasts, drink lots of liquids, mainly water, or tea or coffee with no sugar or milk.

You can also work out, and don’t worry, it’s not dangerous to do that according to the health experts. Some people online said they felt great exercising on their fast, but others have said they felt weak or got a headache. If you do it, take it easy and see how you feel. As for longer fasting, say 72 hours, most health experts say such water fasts are best done when medically supervised.

We found studies online which did say such long fasts have helped people who suffer from hypotension. These fasts can help stabilize blood pressure. We must point out, though, that there have been cases of people dying when doing very long fasts.

In 2010 a woman from Florida died on her 21st day of fasting.

So we advise you to talk to health professionals before embarking on a long fast. You will find lots of people claiming that long fasts, often week-long water fasts, can help your cells regenerate and you become healthier, but a lot more scientific research needs to be done.

Some studies have shown that long fasts have helped people suffering from cancers, heart disease, and diabetes, while also promoting cell re-growth, but as we said, we think you should check first with a doctor and ask them what they think about you doing a fast longer than 24 hours.

Intermittent fasting, though, from what we can see, is safe for most healthy people. Just head to any forum and see what people are saying about intermittent fasting and indeed you will find scores of people saying that they lost weight, felt more mentally alert, while after fasting they just didn’t need as much food as before.

As one doctor said online, too, his clients found fasting a lot easier to do than following a strict diet plan. Looking at forums you will find lots of people saying things like this

Yes intermittent fasting is very helpful. I have lost 30 pounds, went from 20+% body fat to 8% so far from just this March. I have been doing it every day since.

There seems little doubt that many people lose weight when doing these fasts, even just 16-hour fasts. Most people will eat their evening meal early around 5 and then get through most of the morning without food.

While a lot more research needs to be done concerning all the health benefits, just reading what people say about their fasts online lets you know that fasting does work for most people if they want to lose weight, while many people enjoy how they feel doing the fasts. Have you tried fasting? How was it for you? Tell us in the comments.

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Rebecca Marie

Rebecca Marie, MA, LMHC, LPC, MAA is a Licensed Mental Health Counselor and is an expert in anxiety, stress, depression, and relationship issues.

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