Why Low-Calorie Diets Suck

The weight loss industry is a multi-million dollar industry and much of it is extremely frustrating with little to know scientific backing. From diet plans, workout programs, and supplements we are bombarded by “quick” ways to lose 20 pounds. Like most things in life, good things comes to those who wait and work. “Quick” weight loss is usually not sustainable. One of the primary ways people try to lose weight quickly is with low-calorie diets.

Most low-calorie diets say you should be restrict your caloric intake to between 800 and 1,500 calories a day. Think about this…a glass of whole milk (8 oz.) comes out to be 150 calories. So that means on a 800 calorie a day diet, you can have a little over 5 glasses of milk before you reach your caloric limit. Sounds like a lot of “hangry” moments in that persons future.

This simply isn’t enough energy for your body to thrive on. Eventually your body will fight back as it is extremely resilient and it’s only goal is survival.

Side Effects of Low-Calorie Diets

Decreased Resting Metabolism

Your body’s only goal is to survive. It strives to maintain equilibrium of the body and is extremely effective at adjusting to the stimulus it is given, whether to become stronger or to protect itself.

One of the primary mechanisms of survive for the human body during a low-calorie diet is a reduction of metabolism. When the body is faced with a drastic reduction, it works to find a way to adjust.

The first thing to adjust is your metabolism. Through multiple mechanisms, the metabolism will begin to slow in response to an extended exposure to a low-calorie diet.

This is why so many people end up yo-yoing with their weight. Experiencing quick weight loss, followed by an even quicker and greater rebound. People may see immediate results but in the long-term they are not sustainable.

Decreased Muscle Mass

During a low-calorie diet the body will go into survival mode. It will begin to try to minimize any unnecessary organ to help preserve energy for essential life functions or organs.

The body will begin to breakdown muscle tissue, not only to help preserve energy as stated before but to also provide energy as well. Basically your body begins to eat itself. This is one of the ways the weight will begin to look like it is falling off on the scale, but it may not be the desireable form.

Muscle is a calorically needy tissue and is one way you can increase your metabolism. Your body will get rid of this needy tissue for survivals sake. As your muscle mass decreases so does your resting metabolic rate.

The more muscle mass you can maintain during a weight loss phase, the easier it is to lose the body fat that most people are trying to rid themselves of.

Life Sucks

Food is an awesome thing. Most of it is delicious, besides brussel sprouts (YUCK!). It makes life a beautiful thing.

There is no better way to say this, but being on a low-calorie diet sucks. Your mood sucks. Being hungry sucks. Having no energy sucks.

Because you’re not you when you’re hungry

Everything sucks.

Low-calorie diets have been shown to not be sustainable and have actually been linked to depression. High levels of cortisol that result from low-calorie diets have been shown to be the cause of mood disturbances

When the brain isn’t getting enough fuel it finds a way. Whether that be cravings or mood swings, your brain will signal that it needs fuel.

Decreased Performance

While being on a low-calorie diet, your performance will begin to suck. Whether in the weight room or at work, you will begin to suck. It may be more physical in that you just don’t have the energy to lift the weight during your workout, or it could be that your hungry is so distracting you can’t focus at work.

To specifically touch on workout performance, the precious muscle you worked hard to build will breakdown during a low-calorie diet. Less muscle tissue equals a weaker muscle which means a weaker performance.

Just because a workout is hard doesn’t mean it is better. If the workout you did 2 weeks ago with ease feels like absolute hell this week, you probably are not getting enough energy for performance.

Diet Recommendations

There are all kinds of styles of diets out there. The purpose of this article isn’t to debate which diet is better; whether it be Paleo, Keto, low-carb, or high carb.

If weight loss is your goal it is important to understand that calorie deficit, or consuming less calories that you take it in, is of chief importance.

“But I thought you said low-calorie diets are bad??”

Yes I did say that but we can eat a lot more than people think during a weight loss phase and still lose weight. It is important to remember that slow and steady wins the long-term fat loss race.

The first step is to determine your resting metabolic rate.  Now this isn’t the exact number as that would need some specific scientific testing but their are some equations that can help you determine a number that is close. The Harris-Benedict equation (HERE is a calculator) is one way to determine your daily caloric need. The MyFitnessPal app can also help you as well as aide you in food selection and calorie tracking.

For people trying to lose weight, it is my recommendation that they maintain a daily deficit of 500 calories per day. This comes out to a 3500 calorie deficit each week which equals a pound a week. Again a slow and steady approach is much more effective in the long run.

Macronutrients are broken into fats, carbs, and proteins. Like I stated before their are multiple diet beliefs and some of them are based on percentages of the macros. My recommendation across the diet spectrum is to eat .8-1.2 grams of protein per pound of body weight.

I personally prefer more of a carb cycling approach based on if I am working out that day or not. On days where I am working out, my carbs are anywhere between 2-3 grams per pound of body weight and on non-training days I would stick to 1 gram per pound of bodyweight.

Notice I didn’t say carb are bad! They fuel our performance, help preserve our muscle mass, as well as are delicious.


A good training program with a slow and steady approach to weight loss can help you win the health race in the long run. Gross weight loss shouldn’t be the goal but instead we should be looking decrease our fat mass. By making sure we eat enough we can hopefully prevent some of the side effects of a low calorie diet, except that whole shedding a few pounds thing.