Does Fasting Work?

Fasting is the newest diet trend. But is it merely a passing fad, or could this be the next big innovation in weight loss?

First things first, let’s talk about what fasting is. People have been fasting for thousands of years. In fact, in many religions fasting is an important custom. But is fasting a good way to lose weight? This kind of fasting (called “intermittent fasting”) is on the rage, and it generally follows one of a couple methods. Fasters usually have select days where they eat little or no food, followed by days where they eat what they want. Alternatively, some avoid eating for most hours of the day, and instead only eat within a select window of time(say 9:30am to 5:30pm). Common fasting diets include the 5:2 (five days off – two days on) and the 16:8 (16 hours no food – 8 eating).

Of course, we’re left to wonder if this approach to weight loss is effective and healthy. Today’s post will answer that question. As with all diets, you have to decide what works for you. I don’t advocate a specific diet, nor do I claim to be an expert in the field. But there are some principles to keep in mind, and my research below has dug up a lot of useful information.

Greeting from Florida!

Weekly Update:

So this week I’ve had a lot of exciting things happening with my fitness goals. First off, I have to tell you about a challenge my dad and I are having. So both of us are trying to lose weight (although I’m farther along). He decided to challenge me. The official rules are as follows: He has to lost twice the body fat percentage that I do to win. I know that might sound unfair, but the more you have to lose, the easier it comes off. Besides, he seems to think he could “lose three times what I do”. Unrealistic, yes. But I’m gonna beat him either way, so we’ll let him have his fantasies.

I wrote last week about having some concerns with my weight loss. After my most recent weight in, I have to report that I’m quite suprised with the results. My weight has stayed the same, but my body fat percentage has dropped 1.5% (Body fat percentage is just what it says, a way of determining how much of your body is fat. It’s noteworthy that body fat is one of the best ways to track your health. Unlike BMI – which can be way off – body fat gives you a solid idea of whether your weight is healthy.) Crunching the numbers, that means I’ve lost 2.5 lbs of fat, and gained 2 lbs. of muscle in the last two weeks. Because I’m on a diet, I really didn’t expect to gain muscle. So this has been a welcome surprise.

Other than that, life has continued on as usual. Probably the most interesting thing this week was setting up a Veggie Novelist instagram account. If you would like to follow me, my handle is: @veggienovelist . I hope all of you are continuing to progress toward your fitness goals as well.

Until next time, Nathan


Lowered Risk of Disease – Fasting diets have shown positive results in the lab. Subjects who adhered to fasts demonstrated lowered cholesterol levels and lower blood pressure [1]. These results indicate that fasting may lower the risk of heart disease.

Weight Loss – This is what we’re here for, right? So to be clear, fasting can help you lose weight. The golden rule to weight loss is “eat less calories than you burn”. Naturally then, a diet that stops you from eating will induce weight loss. There is, however, a flip side. Some people take the approach of “fasting on fast days, and gorging the rest of the time”. Well, that’s not how weight loss works. Your body is the perfect calorie counter. So if you eat outrageous amounts on off-days, you could neutralize any gains from fasting. In other words, you may not lose weight.


More Challenging – Intermittent fasting may prove more challenging than a regular diet. In a July 1, 2017 study published in JAMA Internal Medicine [2], intermittent fasting was compared with the traditional diet process. Although both groups experienced similar weight loss, the fasting group had a 9% higher dropout rate.

And really, this should come as no suprise. While I was researching for this article, one comment that really stood out was from a fasting advocate. He said: “I only started seeing the results I wanted when I combined intermittent fasting with a healthy diet of real, whole foods and consistent weightlifting.”* That highlights one of the biggest downsides of fasting – it’s makes dieting harder. As this writer said, he had to (1) eat healthy and (2) exercise to see results. With any diet, what are the keys to success? (1) Eat healthy and (2) exercise. So if you’ll lose weight with those two steps, why would you make life harder and add the additional restriction of not eating for extended periods of time? Perhaps it’s just me, but diet and exercise are hard enough. I certainly don’t want to make it harder.

May Not Promote Healthy Lifestyle – As we discussed above, occasional fasting has shown positive results in current studies. So if you see fasting as a part of your new lifestyle, it may be a worthy inclusion. However, if you’re just fasting to lose weight, you’re missing out on one of the most important lessons dieting teaches. To stay in shape, we have to eat healthy (obviously, right?). Which means when you follow a crash diet, you’re not learning to eat healthy. Your diet should include foods you want to eat, and be planned in a way you can keep doing when you’re finished. That doesn’t mean your needs will stay the same. One day, you’ll hit your ideal weight. Then your calorie requirements will go up. You may even set new fitness goals. But your diet now should follow a pattern you can stick to for the rest of your life. The method you use to plan your meals, the rewards you give yourself for being good, even the foods you eat, should all be things you could stick with long-term. Why? Because if they’re not, you’re bound to regain weight. That’s why the way you diet is so important. If you don’t learn to eat healthy when you’re ultra-motivated, how will you maintain your weight once you reach the finish line? So if fasting is just a means to weight loss for you, it’s best to steer clear of this diet.

Muscle Loss – Diehard fasters often swear that fasting does not cause muscle loss, but this simply does not match current scientific evidence. Although a handful of studies are hailed as “proof” that fasting doesn’t burn muscle, the bulk of weight-loss research says otherwise. Time and again, studies have shown that we lose some muscle when dieting. And as we talked about before, without high protein intake that number goes way up. [ , ]. Now if that’s true of people who were still eating everyday, how could someone on a fast avoid losing muscle mass? There’s no way to get enough protein when you’re not eating. Even 16:8 fasts (16 hours no food – 8 hours gorging) still fall short. You see, the body can only process so much protein at a time. (If you eat all your protein at one meal, a large amount of it will go to waste [3]. )

So clearly, fasting diets are setting you up to lose muscle mass. There’s just no way around it. Which begs the question: why not choose a diet that factors in muscle loss?

Feelings of Hunger – This seems to vary person to person. However, many people who’ve tried the fasting diet report intense hunger pains and serious mental fatigue. On the other hand, others find that it’s a much easier approach than several small meals a day. Before starting a fasting diet, you should consider how not eating for extended periods of time would effect you. If you get “hangry” when you eat a late lunch, how would you do skipping entire meals?

One interesting note is in regard to metabolism. You might expect (I did) that fasting drastically slows the metabolism. However, as long as fasts don’t carry on for multiple days, current research indicates that they do not negatively impact the metabolism. Some studies have even seen an increase in metabolism from intermittent fasting.


Fasting is en vogue like Madonna’s single. But as we’ve discussed, it is probably not the ideal choice for someone simply trying to lose weight. Still, increasing evidence indicates that there are health benefits to intermittent fasting. For those willing to commit to the lifestyle, fasting may bring some excellent results. However, the key to healthy living is what we eat and how we exercise. So fasting or not, we all can benefit from continuing to improve in these areas.



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