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Is Intermittent Fasting Better Than Calorie Counting? What the Science Says

  • Breanna Allgood
  • Feb 20
  • 6 min read

By Breanna S Allgood


Intermittent fasting (IF) is a popular choice for weight management, but is time limitation more important, or effective, than calorie restriction? In this post, we’ll explore what IF is, how it can be practiced, as well as potential risks or benefits of practicing IF. 


What Is Intermittent Fasting?


IF is an eating plan that focuses on when to eat, rather than what to eat. It allows for much flexibility in eating windows and structures, making it very customizable to an individual's personal needs. During IF, a person will eat for a selected, and limited amount of time each day. This can take many forms, like, 16:8, which features an eight-hour eating period followed by a sixteen-hour fasting period. 


Within the body, IF has potential to improve body composition via weight-loss, as well as improving metabolism through regular circadian eating patterns. Once a healthy weight has been achieved, it can also lead to stable weight management. 


How Intermittent Fasting Helps Body Composition and Health


By instilling consistent periods without calorie consumption, IF may improve overall body composition by regulating metabolism. This is done through “flipping”, or activating, the body’s metabolic switch. The metabolic switch is described as the body changing from using the liver’s glycogen stores as its primary and preferred source of energy, to instead utilize fatty acids. This occurs when an individual has reached the point of negative energy balance, that being a caloric deficit (Anton et al., 2018). Thus, when glycogen stores are fully depleted, the body turns from fat storage to fat use in order to maintain function. 


Even though there are benefits to IF, studies have shown that, when compared to daily calorie restriction, IF does not seem to be any more effective. In a randomized clinical trial, Trepanowski et al. (2017) compared the effectiveness of alternate-day fasting (ADF) to the effectiveness of daily calorie restriction. Three groups were present, the first practicing ADF, the second following daily calorie restriction, and the third being an unchanged control group. Measurements were taken in the form of weight loss/maintenance, protection against cardiovascular disease, and overall adherence to diet. By the end of the trial, researchers found that the ADF group did not actually produce any different results than the daily calorie restriction group in terms of these measurements. Though, they did see a greater dropout rate of those within the ADF group, showing they struggled more with dietary adherence. The author does acknowledge some limitations in regards to their finding on weight loss. It is stated that, due to the dropout rate being higher than anticipated, their ability to measure the difference in weight loss dropped from around 80%, to close to 60%. Therefore, IF is not an invalid approach to achieving better health, there is simply more than one path a person can take, which allows them to utilize the approach that fits them best. 


Picking An Eating Window


Many different “eating windows”, periods of time where one can eat freely, can be followed to practice IF. Below are some common forms of IF, as described by Dietitians Australia (2022):


16:8: The 16:8 plan features an eight-hour eating window, and a sixteen-hour fasting period. This can look like eating between the times of 10:00am-6:00pm, where the first meal of the day is consumed after 10:00am and the last is consumed before 6:00pm. Fasting will then take place until the following day at 10:00am.


5:2: This method is slightly different from the 16:8 plan. To follow the 5:2 method, a person will eat regularly for five days of the week, but they will limit caloric intake to 500-600 kilocalories (kcal) for two, nonconsecutive, days of the week. This may look like eating a limited amount of calories on Tuesday and Friday, then eating maintenance calories every other day of the week. 


Eat-Stop-Eat: In following the Eat-Stop-Eat method, a person will fast for a full 24-hour period once or twice weekly. This makes it similar to the 5:2 method, where calories are restricted on nonconsecutive days of the week. Using this method could look like fasting all of Wednesday, and eating normally on other days. It is optional to include fasting more than once weekly. 


Alternate-Day Fasting: Alternate-day fasting is very similar to the 5:2 method in its approach to IF. It features a “fast day,” where individuals will consume around 25% of their maintenance calories, typically around 500kcal, which is followed by a “feast” day where the person may consume food freely, not restraining caloric intake for that day. This will then alternate daily to form the cycle called “alternate-day fasting.”


Practicing Intermittent Fasting


Here is a sample of the 16:8 plan discussed in this blog:


16:8 Plan

Breakfast - 10:00am

Lunch - 1:00pm

Dinner - 5:00pm


The last meal is finished prior to 6:00pm, then the 16-hour fast begins until 10:00am the next morning. Since IF typically reduces the number of calories a person consumes, it is important to be mindful that proper nutrients are present in the diet to avoid any form of deficiency. 


Below is a list of some whole, nutrient-dense, foods that will support the body during IF:


  • Lean Proteins (eggs, fish, poultry, beans, greek yogurt) - Muscle maintenance, satiety

  • Healthy Fats (salmon, avocado, olive oil, nuts) - Hormone production, brain health

  • High-Fiber Carbohydrates (oats, sweet potato, chia seeds, green peas, black beans) - Steady energy, supports digestion

  • Fruits and Vegetables (leafy greens, berries, squash, carrots, peppers) - Vitamins/minerals, antioxidants 


Should You Consider Intermittent Fasting?


IF can help improve health in many ways, especially in regards to body composition. It should be understood though, that IF will not work for everyone, and it can take time for a person to find the method that helps them in achieving better health. Before committing to any form of diet, one should always research background information on said diet to learn how it could affect them. Attinà et al. (2021), states that there are limitations for certain individuals in regards to IF. For children and adolescents, practicing IF presents some physiological and psychological dangers, which can impair growth. Concerning pregnant and breast-feeding women, IF is not recommended as it would limit specific nutritional needs, as well as inhibit necessary energy requirements. The same can be said for those who are 75 years of age and older, as well as those who are classified as underweight, and more. If you fall into one of these categories, seeking professional advice from a licensed doctor and/or nutritionist will always be the best, and safest course of action. 


Final Thoughts


IF poses many great benefits for those who decide to implement it into their lifestyle. It can help improve body composition, as well as regulate metabolism, by “turning on” the metabolic switch which allows the body to use fat stores for energy. However, IF is not the only proven way to accomplish these things, as daily calorie restriction also brings these benefits through a shared mechanism, a calorie deficit. Thus, the way that you do it is not so important, as there is no magic cure to improving body composition. What is important, is finding the diet that works best for your body and lifestyle, and being able to stick to that diet long-term. To do this, one should prioritize eating whole foods for things like: satiety, hormone production, healthy digestion, and vitamin intake via food. Overall, though it is not the only path a person can take to achieve their desired results, IF is a great way to improve personal health.


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