Fad diets… 

 Do they work?

 Are they beneficial?

 Can they be harmful?

 Let’s dive into fad diets and look at the facts, the myths, and alternative options to help you hit your goals! This time of year, we are often bombarded with “quick fix” plans and methods that are guaranteed to “get you results in 30 days”. 

 We recently did a poll on Instagram asking how many people have done a “fad diet”. 111 people responded, with 101 people saying that they had done a fad diet…

 So, that is almost 91% of people being polled stating they had done a fad diet. Interestingly, of the 91% who said they had done a fad diet, 94% of these people stated they were unable to maintain the weight/body composition changes they achieved through that fad diet. Why is this?!

 First off, let’s explore what fad diets are!

Did you know that fad diets have been around for centuries? In fact, the word “diet” comes from the Greek word diaita (4). During the 19th century Greeks and Romans popularized “dieting” for aesthetic purposes (4). Yep, you got that right, humans have been intentionally using food to change their bodies for that long, and while we have come a long way in our education of proper nutrition, some fad diets still persist today, hence the need for this blog! 

 In the 1820’s, Lord Byron of England popularized the “Vinegar and Water” diet as a way to lose fat. While this may sound silly to read about, the principles of this diet are in alignment with other fad diets. In fact, to be considered a fad diet these key characteristics are present (4):  

  •     Promise weight loss of more than 2 lbs/week
  •     Limit the range of food types included in the meal plan
  •     Propose “miracle foods” that help fat burning
  •     Characterized by low calories and low micronutrient intake
  •     Unsustainable long-term, often leading to inability to adhere and weight regain (often more than prior to beginning diet). 

 So, while the vinegar and water diet may be a diet that you can obviously view as a “fad diet”, other diets you may not realize are. Checkout this table below debiting numerous fad diets that are still practiced today:

Have you ever tried one of these diets? If so… how did it work for you?

 If you did notice that you lost weight when doing a fad diet, you may be asking why. Well, let’s look at the science behind this weight loss!

 As previously stated, fad diets encourage weight loss of greater than 2 lbs/week. Sounds fantastic right?! But we must look at what this “weight” is. 

 Unfortunately, weight lost at this rate most likely is NOT fat, but instead, it is a loss of weight from water due to the dramatic decrease in calories, specifically carbohydrates (4).  Did you know that each gram of carbs holds 3 grams of water (4)? So, when you dramatically cut carbs (as most fad diets do), you will lose water very quickly. This dip in the scale is why fad diets are so intriguing to those who do not understand this concept- they see the drop on the scale and think “wow, its working!!”. However, again this is NOT solely fat loss. This is why many people who have done the keto diet find it so motivating- it is focused on a very low carb approach, which creates rapid weight loss with a large portion of that weight loss being from water (4).

But, after the first week or so, if an individual is able to adhere to a fad diet, which is extremely difficult due to their restrictive nature, the individual may begin to lose more weight. At this time, they may be losing fat, but it is also very likely they may be losing muscle (3). 

 This is very important to understand, because it is not “weight” we want to lose when trying to change our body composition, but rather, fat. If an individual is too aggressive with their calorie deficit and drops calories too low (which fad diets do), then their body is more likely to burn and lose muscle in addition to fat during the calorie deficit. This not only decreases the likelihood that a person will achieve the body composition goals they are after, but it is also detrimental to their overall health (3). Whenever we think of muscle, we want to think of it as our body’s “armour”. Muscle is what protects us from disease and illness, it helps prevent us from falling and breaking bones, it helps support our metabolism, and it ultimately is what allows us to have that “toned” physique everyone wants (3)! Having muscle on our body is essential for health, and each time a person does a fad diet and begins the cycle of drastically cutting calories through these diets, they risk losing precious muscle mass. 

 As we stated, this loss of muscle mass impacts our metabolism. Please check out this image below:

As you can see, basal metabolic rate makes up 70% of calories burned each day. When you compare it to the other sections –  TEF, NEAT, and EAT  – basal metabolic accounts for a HUGE amount of our daily calories burned. For more information on this breakdown, check out our Strength Training and NEAT blog HERE

 What exactly is the basal metabolic rate?

Having more muscle mass on our bodies increases our basal metabolic rate, and therefore increases our ability to lose fat and maintain fat loss. When we do extremely low-calorie diets like fad diets, our basal metabolic rate lowers, which is part of why rapid weight (and fat) regain occurs.  Once a person resorts back to “eating like normal” after a fad diet- their metabolism has adapted due to their low-calorie intake and potential muscle loss. 

 Why do our metabolisms adapt?

 As you saw in that image, basal metabolic rate makes up approximately 70% of calories burned each day. BUT, if we eat below or very close to our basal metabolic rate, our body is forced to down-regulate its energy expenditure in an effort to keep you alive. This is NOT your body “fighting you”, but rather it is your body trying to protect you. For reference, many fad diets drop calories at or below 1200 calories per day, with some dropping as low as 800 cals/day. To frame this in a way that depicts how harmful this can be, in a study done by Manini (2010) they found that even amongst 50-year-old individuals (and older), the average basal metabolic rate was around 1500 calories per day. Remember, basal metabolic rate is the number of calories you burn each day through performing basic life-sustaining activities, like breathing. This does NOT account for energy burned form walking, or your CrossFit or spin class, or playing outside with your kids. With this degree of caloric deficit, your body has no choice but to put its hands up and say “hey, I guess we gotta slow down our metabolism and lose some of this muscle because we are not getting fed”. Our bodies do not know that a McDonalds is across the street, or that you have a fridge full of food. Therefore, it does what it thinks it needs to keep you safe by slowing down your metabolism to protect you! 

 As we said, fad diets DO promote weight loss, however, this is not necessarily the type of weight that you want to lose as it is often a combination of water, muscle, and fat. If you want to understand more about energy balance, and the approach we suggest on how to create SUSTAINABLE energy balance, please check out our energy balance blog HERE :

 Now, let’s talk about fad diets and performance. 

If you are someone who partakes in any form of training (resistance training, running/cardio, sports, dancing, etc), then it is important to understand how fad diets can impact your performance. 

 Research suggests that when athletes partake in fad diets, their performance suffers drastically as they experience fatigue, headaches, and lowered strength (5). While a lowering of calories is viewed as the most detrimental factor to performance, composition and timing of food also impacts performance (5). In research by Love (2019), they found that athletes suffered a decrease in performance when using a ketogenic diet approach. Remember, a ketogenic diet is a drastic decrease in carbs while being very high fat and moderate protein. Carbohydrates are our bodies preferred source of energy, when carbohydrates are drastically dropped, energy and therefore performance can suffer.

Whenever you approach any lifestyle change, you have to ask yourself… Can I do this forever? For example, when looking at a diet that provides prepackaged/preportioned meals or requires you to follow a specific meal plan, you must ask yourself: Can I eat these meals forever? Often, the answer is no, because plans such as this do not allow for date nights out, trying new foods while traveling, eating foods you truly enjoy, or having the tools to adapt when LIFE just happens!

This also applies to cleanse or detox style diets, what happens after the cleanse/detox ends…?

Do you simply resort back to how you were eating before? Did you learn anything about nutrition or how to fuel your body from doing a cleanse? Likely not. This is part of why fad diets are still around today, from a marketing perspective they are FANTASTIC because they promote weight regain, meaning a guaranteed return customer! This leads to a vicious cycle of fad dieting. 

 So, as we discussed, fad diets DO promote weight loss by putting you in an aggressive calorie deficit,  cutting out whole food groups, or only allowing you to eat certain foods. But the diet is UNSUSTAINABLE leading to regain of whatever weight was lost when a person returns to “normal” eating. This leads to the Viscous Cycle of Dieting (aka Yo-Yo Dieting) – Referencing the above image: You go on a diet that involves a large amount of restriction -> your willpower eventually depletes leading you to “fall off” the diet -> typically leads to emotions of guilt/shame where you go back to your previous habits -> which often leads to weight regain (often more than what you had originally lost!)

Does this sound familiar? We do want to emphasize that there is another way!!!

 At YQL Nutrition, we coach clients on the power of HABITS! We encourage our clients to take inventory of what choices they are currently are making, and from there, we help them implement small changes over time to create positive change! We promote flexible dieting, understanding what is IN your food and what portions are appropriate for YOU and your goals, and how foods make you feel. From there, we can begin to discuss how to alter your intake to reach your goal, but this is done in a SUSTAINABLE way with longevity always at the forefront. Once an individual reaches their goal, whether it be fat loss, athletic performance, or muscle building, we ensure that we spend adequate time with them at maintenance calories. What are maintenance calories? Checkout this image below:

Maintenance phases are SO important for overall health, including the health of our metabolisms! With each client, we walk them through timelines for their goals, and we make sure we have adequate time at maintenance before and after other goals, such as fat loss or muscle building. 

As you can see, maintenance is where we should be spending the majority of our time- it is where we are focusing on overall health, relationship with food, and learning to intuitively eat (if a client is interested in this). When a new client begins with a maintenance phase and a focus on building healthy habits FIRST before starting a fat loss phase, this improves their ability to be successful in their fat loss phase and sustain their results long-term. If you would like to learn more about what habits we focus on, and how to incorporate habits into your life, we are starting our HABIT CHALLENGE for the month of February! This is an amazing opportunity to focus on adding habits into your daily life, which are the CATALYST for transformation!  Link to Join our Habit Challenge HERE (sign up until Jan 30, 2022)

 To summarize…

 Fad diets promote a cycle of yo-yo dieting which can be harmful to your metabolism, your relationship with food and with your body. There IS another way to create change within your life if you have body composition goals, and that is by focusing on building sustainable habits that are in alignment with your goals. Before beginning any endeavour with your nutrition, we encourage you to ask yourself “can I do this forever?”. If you can’t, then ultimately you are setting yourself up to fail. 

 If you have been stuck in the yo-yo diet culture of fad diets and need 1:1 guidance from a coach to help you reach your goals, we encourage you to reach out to us through using THIS LINK

 We hope this blog provided with you a scientific perspective on why fad diets do not serve you or your long-term goals, and that you are now open to trying a new, sustainable approach through focusing on habit formation.

 All the love, 

 Robyn & Megan, YQL Nutrition. 




  1. Bastin, S. (2004). Fad Diets. Available at: http://www2.ca.uky.edu/hes/fcs/factshts/fn-ssb.119.pdf 
  2. Centers for Disease Control and Prevention. (2014). Healthy Weight – it’s not a diet, it’s a lifestyle!. Available at: http://www.cdc.gov/healthyweight/index.html
  3. Current, Austin. Science of Strength Training. DK Publishing. Kindle Edition.
  4. Khawandanah, J., & Tewfik, I. (2016). Fad diets: lifestyle promises and health challenges. Journal of Food Research, 5(6), 80-94.
  5. Love, P. (2019). The Effects Of Low-Carbohydrate Fad Diets On The Performance Of Competitive Tennis Play. JOURNAL OF MEDICINE, 25.
  6. Manini TM. Energy expenditure and aging. Ageing Res Rev. 2010 Jan;9(1):1-11. doi: 10.1016/j.arr.2009.08.002. Epub 2009 Aug 19. PMID: 19698803; PMCID: PMC2818133.