The Problem with Low Calorie Diets

Apr 15, 2018

You’ve seen it on the front page of health magazines or you’ve heard about it through Doctor Oz. Fad diets are everywhere! When it comes to losing weight, people will try just about anything from Atkins, Paleo to Ketogenic diets. Yet, the main ingredient in the majority of these diets is a caloric restriction. It’s safe to assume that the majority of people trying to lose weight understand that you need to burn more calories than you consume. Therefore, is continually lowering your calorie intake the answer to losing those dreaded pounds? Well, it can easily get the job done. However, if not done properly, your health may be at risk. I’ll let you decide what’s more important… Looking good naked or having a long-lasting health?

How do we burn calories?

It’s a common belief that lowering your caloric intake will speed up weight loss. This is true as the facts don’t lie. In order to lose weight, you must burn more calories than you are consuming. How does one burn calories? Through your metabolism. Essentially, your metabolism is your cost of living (breathing, pumping your blood, regulating your core temperature..). It is the baseline energy requirement (calories burned) that your body needs to live. That being said, there are factors that can affect one’s metabolic rate:

  • Physical activity: increases your metabolism for the duration of the activity. All body movements require energy, therefore the more you move, the more you burn.
  • Muscle mass: Muscles require more energy than fat cells, therefore the more lean mass you have, the more calories you burn.
  • Age: as you age, your metabolism gets slower. We lose muscle mass and don’t move as much. This is why we often see people gain weight as they get older. They consume the same amount of calories however their metabolism is burning less.
  • Body size: The bigger you are, the more mass you need to move around. This means more calories will be burned.

There are many other factors that can affect your metabolism such as hormonal imbalances or environmental temperatures. Yet, for the sake of this article, we’ll keep it simple. To help you understand the metabolism process, we will use the car analogy. Imagine your body as a car that is on 24/7. The following will describe each metabolic function compared to that of a car’s:

  • Metabolism: Your metabolism is the car’s idle. It burns fuel even when it’s not moving. Now if your car idled for an entire day, that would add up to a lot of burned fuel.
  • Physical Activity: Is comparable to driving down the highway for an hour a day. It burns fuel at a faster rate, yet for a shorter period of time.
  • Muscle Mass: Imagine your muscles as the car’s horsepower. The more you have, the more fuel you’ll burn while in idle and while driving down the highway.  
  • Body Size: The bigger the car, the more weight the engine has to move. Therefore, more fuel will be burned.
  • Age: An older car gets less efficient and often spends more time in the repair shop. Therefore, the car isn’t used as much (especially for long road trips) so less fuel is used and burned.

Needless to say, if you were to compare all these factors in a 24 hour period, the idle would win as the major fuel burner. All the others, simply add or subtract from the original fuel burned by the idle (aka metabolism). Obviously, being more physically active and having more muscle mass will result in a higher daily metabolic rate.

As you can see, your metabolic rate is the major player in burning calories and is key to losing weight or preventing weight gain. So why am I telling you this and where do low-calorie diets come into play?

Lowered Metabolism

Well, when someone embarks on a diet with limited or very low calories, they will notice rapid weight loss followed by a plateau. During this plateau stage, the body’s metabolism will adjust itself to match the low-calorie diet, therefore, lowering its energy demands. It stands to reason that the body is an adaptive machine and won’t let you trick it for too long. This is the body’s survival mechanism in order to save itself from wasting away. Therefore, when individuals return to a regular caloric diet, they suddenly gain the weight back or more because their metabolism hasn’t adjusted to the caloric change yet. This is known as the “Yo-yo effect”. Click on the link below for a chart illustrating the yo-yo effect.

Cost of Low-Calorie Diets

To avoid this roller coaster of weight loss/gain, many people believe they should continue dropping their calorie intake since that is what caused them to lose the weight in the first place. However, this will result in an even lower metabolic rate and could lead to serious malnutrition and health issues which are beyond the scope of this article. Building a good metabolism doesn’t happen overnight. It takes a long time and a lot of hard work. As mentioned earlier, it is inevitable that age will decrease your metabolism, therefore you want to keep it as high as possible for as long as you can. That being said, if one decides to pursue a low-calorie diet, one must be very careful and should seek supervision from a health professional.

Nutrient-Dense Vs. Calorie-Dense Foods

So what can you do instead of following a low-calorie diet that might compromise your metabolic rate?

Professionals recommend that you eat more nutrient-dense foods rather than calorie dense foods. This method allows for a lower calorie count, yet not excessive or dangerous, and provides the nutrients necessary for good health.

What’s the difference one might ask? Well, nutrient-dense foods have a bigger quantity and better quality of protein, carbohydrates, fats, minerals, and vitamins. In general, these foods haven’t been modified and are in their natural state. Essentially, they are your best bang for your buck. They provide your body with all the nutrients it needs in the least amount of food. Examples would be vegetables, fruits, fresh meats. For a more in-depth list check out our recommended Pure’s Grocery Store Checklist.

Also known as energy-dense foods, calorie-dense foods provide more calories per serving and have less nutritional value. The typical culprits are foods or beverages that are highly processed, have a high sugar count, and include alcohol or trans fats. Examples include cakes, cookies, chips, beer, ice cream and the list goes on. These foods often have “empty calories” which give no nutritional value to the body. These “empty calories” provide the body with energy yet provide no nutrition in the way of vitamins, minerals, protein, fiber, or essential fatty acids. Therefore, if this energy isn’t used (by exercising), these calories will be stored as fat and have no other beneficial function towards your health.

It’s up to you. If you want to look good for a photoshoot or a day at the beach, a low-calorie diet can work wonders. Yet, don’t expect the results to last for a long period of time. If your goal is to get lean and stay lean, implementing healthy habits over time and eating nutrient-dense foods has been proven to give lasting and healthy results. It’s all about small steps and progression. Build your foundation for years to come. Don’t rush weight loss as it takes time!


Paul Bissonnette B. Kin, CEP, CSCS, FMSC, Pn1


  • Berardi, J., & Andrews, R. (2015). The Essentials of Sport and Exercise Nutrition Certification Manual (Second ed.). Precision Nutrition Inc.
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