Fasting vs. Calorie restriction for weight loss. Which one is for you?

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Key Points

• Caloric restriction in the long-term is a poor choice for weight loss; it is much better to do time-restricted eating (fasting).
• Caloric restriction can contribute to osteoporosis and will deplete your willpower reserves.
• If you aren’t able to fast, then opt for a keto diet to mimic the effects of fasting.
• Calories do count in a keto diet, however, you will want to naturally eat less doing keto because of the ketosis.
• Start fasting very slowly at 12-hour intervals, and then gradually increase your length of time per week. [/callout]

Does calorie restriction seem taxing for you?

Are you wanting to lose weight but hate counting calories on your smartphone app? I think a lot of us feel this way! Even though I have a type-A personality and love counting and tracking, I wouldn’t say I like inputting calories. So, in my life, I have figured out an easy way to keep track of my food intake, which is very user-friendly. What is this method?? It is fasting or otherwise known as time-restricted eating. In this article, I am going to explore fasting vs. calorie restriction for weight loss. Even if you can’t fast, you will be satisfied with this article as I will give you a better alternative than calorie restriction!

First, let’s talk about caloric restriction

Okay, before we talk about fasting vs. calorie restriction, I want to touch on the latter(calorie restriction). I am going to start by telling you that I am not a fan of caloric restriction. First of all, it doesn’t work, and second of all, it is depriving. So, that being said, this article is to strongly discourage you from doing it. You may be wondering, “well, if I can’t fast or do caloric restriction, then what can I do?” Don’t worry! I will explain below.

Weight loss

Studies showing no benefits of caloric restriction

Let me begin by giving you a study on how calorie restriction doesn’t work. It turns out that even the best study done on caloric reduction as a path to lasting weight loss was a failure. The Women’s Health Initiative, a gigantic randomized controlled trial, followed almost fifty thousand women over seven and half years. One group of the women followed a low-fat, low-calorie diet high in grains, fruits, and vegetables and reduced their total daily calories by 361 calories; their percentage of calories from fat was reduced from 38.8 percent to 39.8 percent. They also increased their amount of exercise by 14 percent. The other group followed their usual diet. The expanded exercise group’s expected weight loss for the low-calories was thirty-six pounds per year or 252 pounds over seven years. The other group was not expected to see any weight loss.

So what was the outcome? Well. The results shocked everyone involved. The actual difference in weight loss between the two groups was not even two pounds! Worse still, the average waist size in the low-calorie, increased-exercise group grew from 35 to 35.4 inches ⁷. 

Increased risk of osteoporosis in postmenopausal women

So what is another negative impact on caloric restriction? Well, number one is if you are a postmenopausal woman, it may increase your risk of osteoporosis. “Although much of the data supported caloric restriction as a means to increase longevity and decrease the incidence of illnesses associated with aging, there is now there is evidence indicating that such restriction could increase the chances of osteoporosis².

Restricting your calories will deplete your willpower reserves

Yup, we have reserves for our willpower! Some studies suggest that our amount of willpower in a given day is a real thing, and it’s limited. Every time you exercise a bit of willpower, you drain your reserves⁸. There is nothing worse for your willpower reserves than caloric restriction! There was a study in the year 2000, which showed that students who had to refuse tempting snacks and/or control their emotional expressions to food stimuli lacked willpower in subsequent tasks⁹.

Now, let’s talk about fasting

Now, I will delve further into fasting vs. calorie restriction and discuss which one works! You’ve probably already guessed it! Yup, fasting. Fasting(time-restricted eating) is very effective for weight loss and much more straightforward than caloric restriction. It also doesn’t deplete the willpower reserves! When you fast, you put your body into ketosis but eating meals in a small amount of time. Ketosis means that your hunger pangs will decrease, and temptation during the fast will go away.

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Even if you are not following a keto diet per se, you will still achieve at least a mild ketotic state by fasting. The choice to fast is a good one because you will eliminate the worries of, “I forgot to input this into my app or what will I eat for ______ meal?” (Ugh, I hate having these questions).[/callout]

It doesn’t matter which diet you follow, paleo, carnivore, keto vegan, keto vegetarian, etc.; fasting is a great compliment to any of them. When you go for prolonged periods without food, your body tends to reset itself. By this, I mean that the bad cells are eliminated from your body, and you regenerate new stem cells. You will also gain mental clarity during a fast and achieve many other benefits( weight loss being one of them). The fantastic assets of fasting are beyond the text of this article!

What do the studies show?

Intermittent fasting for weight loss

Some findings suggest that intermittent CR ( fasting and going without food)may be more effective for retaining lean muscle mass³. Also, in another study performed by the researchers at the University of Illinois in Chicago, 23 obese volunteers followed time-restricted eating (intermittent fasting)diet for 12 weeks.
The participants ate only between 10 am and 6 pm, without any restrictions on the type or quantity of food they consumed. Since they were eating in a small interval, these people showed that they ate an average of 350 calories fewer every single day even though they were no required to count calories OR worry about how much they were eating⁴.

Try to follow a low-carb diet at least while fasting to keep your body in fat-burning mode

The results of these findings are very reassuring. As I mentioned before, you don’t have to do a keto diet if you are fasting, as you will naturally eat less. However, even though I said that I think that at least doing a lower carbohydrate diet would be good to follow with fasting. The reason for this is because you will keep your body in fat-burning mode(ketosis), which will make it easier to fast.

How much weight can be I lose with intermittent fasting?

According to a systematic review of 40 existing studies, intermittent fasting is effective for weight loss. The results of all these studies showed that participants who started fasting lost an average of 7 to 11 pounds throughout 10 weeks ⁵. Another study showed that simply limiting one’s daily eating window to 10 hours for three months can lead to significant weight loss  ⁶.

So what can I do if I can’t do calorie restriction or fast?

Okay, so are you stumped with the whole fasting vs. calorie restriction conundrum? If you are one of them, I suggest a keto diet to mimic fasting and stay full. Some people aren’t able to fast or have contraindications, and I know this. If this is you, I would choose to do the keto diet instead of restricting your calories. When you decide to do the keto diet, you will naturally find that you are less hungry. Also, when you follow a keto diet, you are essentially mimicking fasting by getting into ketosis. Why bother counting your calories when you can choose to make things so much easier by following a keto diet plan. Even if you don’t eat meat, you can still opt to be a keto vegetarian or keto vegan. Get away from the calorie counting and carbs, and come on over to the keto side!

Do calories count at all?

Now, even though I do say, “caloric restriction doesn’t work,”, it is important to remember that calories still count! The cool thing is that when you do a keto diet or fast, you will find that you are not as hungry due to the ketosis.  So what happens is that naturally, you will consume a lot fewer calories from being more full due to the lower carbs. If you want to read more about calories and keto, then you can go to my Keto Biometrics Part 2 post.

How do I start fasting?

Fasting does not have to be complicated. I always recommend that people start very slowly at 12-hour intervals and then increase their intervals over time. For example, let’s say that you wanted to begin fasting this week. You would first start by having your last evening meal by 7 pm tonight and then not eat until 7 am the following day. You would do this for a week and then would increase the intervals every week. So, if you found that you were doing good with ending your meals at 7 pm, then the following week, you would try to go until 8 am the next day for a 13 hour fast.

You can keep going until you’ve achieved your fasting goal. As I mentioned before, it is best to stick to at least a lower carbohydrate diet to make your hunger more manageable during the fasts. If you want to learn how to manage appetite fast, please read my article called How To Reduce Hunger Pangs While Fasting[ 8 Strategies].

In conclusion

In conclusion, when deciding between fasting vs. calorie restriction, you should choose fasting or time-restricted eating. Are you one of those who can’t fast? If so, then choose a keto diet to get fasting-mimicking benefits! If you liked this article, please come on over to the HKG tribe and subscribe to my email list. I would love to have you as part of the tribe!

[toggle title = “References”]
[callout]Madeo F, Carmona-Gutierrez D, Hofer SJ, Kroemer G. Caloric Restriction Mimetics against Age-Associated Disease: Targets, Mechanisms, and Therapeutic Potential. Cell Metab. 2019 Mar 5;29(3):592-610. doi: 10.1016/j.cmet.2019.01.018. PMID: 30840912¹.

https://www.endocrinologyadvisor.com/home/topics/bone-metabolism/osteoporosis/²
Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obes Rev. 2011 Jul;12(7):e593-601. doi: 10.1111/j.1467-789X.2011.00873.x. Epub 2011 Mar 17. PMID: 21410865³.
Gabel K, Hoddy KK, Haggeerty N et al. Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutr Healthy Aging.2018 Jun 15; 4(4): 345-53. doi:10.3233/NHA-170036⁴.

Cole, Will(2021).Intuitive Fasting: The Flexible Four-Week Intermittent Fasting Plan to recharge Your Metabolism and Renew Your Health. New York: Penguin Random House⁵.
Wilkinson MJ, Manoogian ENC, Zadourian A, et al. Ten-hour time-restricted eating reduces weight, blood pressure, and atherogenic lipids in patients with metabolic syndrome. Cell Metabo. 2020;31(1):92-104.e5.doi:10.1016/j.cmet.2019.11.004⁶.
Fung, J., & Moore, J. (2016). The complete guide to fasting: heal your body through intermittent, alternate-day, and extended fasting. Las Vegas: Victory Belt Publishing⁷
Avalon, M., & Fragoso, S. (2018). What when wine: lose weight and feel great with paleo-style meals, intermittent fasting, and wine. New York, NY: The Countryman Press, a division of W.W. Norton & Company^8,9.

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