14 Reasons Why Most Diets Fail According to Science

You tried anything and everything you read on diet books, but no success. 

You cut calories, eliminated fats and carbs, gave up cheat meals, swore off sugar and sweets and even counted how many times you chewed, but your scale wouldn’t budge.

Sounds familiar?

Let’s start with this: It’s not you. 

According to North Dakota State University, 95% of diets fail (ref.1), and some even say the stats are closer to 99%. 

But then, you hear success stories. You’ve seen those photos. You think to yourself how could it be? Are all diets bad or just some? 

You want to believe, but skepticism gets in your way. We hear you, and quite frankly, you have all the right to be doubtful, cautious and down right skeptical. 

Whether you believe diets work or don’t work. Your are right either way.

Most diets don’t work, but there are few that work under certain contingencies.

This post is all about how to become the successful, thriving 5%. 

In a big picture, there are two reasons why most diets don’t work. 

1. They are too extreme. 

Most diets are too extreme that they can’t possibly be part of your life permanently, in a healthy way ever. 

Crash diet, starvation diet, extreme elimination diet, all fall into this category and collectively called fad diets. 

Too little food to sustain you through your normal activities let alone exercise or any vigorous activities. 

Because once you get on, you most likely get cursed to gain all the weight back and more when you return to your normal eating, you will end up fatter than when you started. 

No matter how quick you need to lose weight, slim down and transform your body, don’t fall for these diets. You don’t have to put a curse on your weight. Life is full of challenges without it. 

That leads to my next point. 

Diets that are NOT gimmick, fad, crash or starving type include Paleo, vegans, low / high carb, low / high protein, low / high fat diets. 

Many are based on the sound principles. They are neither gimmick nor fad. They are legit in more ways than you can image. 

They all have millions of followers and counting. They are simply too big to fail or too popular to be wrong. Right?

Not exactly.

2. They are just not right for your body. 

Most of these legitimate diets’ teachings are universal and “one-size-fits-all”. If you don’t see anything wrong here, imagine a clothing store carrying only one t-shirt size. 

Some customers are fine with it, but for most, the t-shirt will be too big, too tight, too small or too loose.  

Our bodies (including yours!) come in many different shapes, sizes and built.

Trying to apply a low-fat diet because you heard your girlfriend lost some weight on it is like buying the same t-shirt in the same size your friend bought because it fit her. Unless it’s your twin sister, it’s best to buy a shirt in the size that fit best for you.  

Don’t get me wrong. 

These diets can work, if your body type is well suited for it. 

But the real question is, how do these diets really know if you are right for them? 

The truth is, they don’t. 

Most diets have no clue what works for you. 

They just know it works for some, but they just don’t know if it’d work for you. 

Imagine this.

You are a zookeeper. Different animals eat different foods. Some only eat grass; some eat meats. Some eat insects and some eat fish. As a zookeeper, it’s your job to understand what animals eat what and you feed them accordingly. Right?

You do that because their health and bodily functions depend on it. 

It’s not too hard to picture that.

But how about us? 

We are not as diverse as animals (thank goodness!), but we come in many different body types and shapes. Your rate of oxidation, metabolism and hormone balance are different from other women.

Some are muscular and more athletic built. Some are rounder and curvier. Some are thin, slim and tall. It’s all because we have a different body type, rate of food processing and burning it.

Difference in how much of muscle fibers we tend to carry and maintain also contribute to your body composition and your weight loss, but let’s not complicate things too much.

Foods is medicine.

It helps you optimize your hormone balance, slow down oxidation that’s too fast and speed up metabolism that’s too slow.

It helps your body operate efficiently and drop extra pounds and excess fat. 

But when one diet discipline gives “one-size-fits-all” way of eating to everyone, it completely ignores what you and your body actually needs.

It ignores how fast your current metabolism is and whether you need to boost it. It ignores how fast you tend to convert food into energy, how much tolerance you have for particular food groups and whether you need to slow down oxidation and support your body better by not taking in so much of what your body shows reactions to.

And most importantly, it ignores whether you are meeting your body’s nutritional needs in a way it can properly function.

It tends to ignore all those essential elements that make up you and your body.

In stead, you’ll have a general approach that may or may not fill the needs of your body.

And when you get it wrong, you can completely mess up your metabolism, make fast oxidation faster (not a good thing) or slow oxidation slower (not a good thing either!), which hinders you from losing weight and burning fat.

They make your body cling to the fat that it has and take every opportunity to store more. It’s a vicious cycle you don’t want to get yourself in. 

And all these wrong turns are everywhere in the arrays of “heath foods” and “healthy diets”.

Let’s take a look at a “healthy wholesome fruit” and see how it can improve or disturb your health and weight loss depending on how appropriate it is to you.

Take an orange for example.

A fruit everyone loves and always a healthy choice. Right?

Not entirely so.

If you are a fast oxidizer, oranges and other citrus fruits may not do well with your body, as they are high in potassium, sugar and citric acid, which directly accelerate fast oxidative processes, worsening the imbalances of fast oxidizers.

But they are perfectly fine, healthy fruit options for people with a balanced to slow oxidation rate, and those elements that cause problems for fast oxidizers have little to no effect on them.

Let’s look at another example from a different macronutrient group.

Take a look at a piece of steak. Grilled, broiled, oven cooked, or any way you like it.

For a person who does well with high-purine proteins, it makes a great meal.

The high-purine from the steak slows down the rate of your food to energy conversion and prevent insulin spike. Their body type thrives with meaty meat and knows exactly how to use it for good. There is no reason to fear or avoid steak; rather, they are encouraged to include it in their diet.

But for a person who tends to slowly convert food to energy, high-purine protein like steak (red meat) can slow down the rate even more and potentially cause your body to send the starvation response, which triggers fat hoarding. It’s ok to have it once in a while, but it’s best not to be consumed everyday.

The takeaway here is, the only way, you can really make dieting work for you is to know your body including its characteristics, needs, strengths and weaknesses.

Find out what your body needs and what’s really holding you back from losing weight and fat. Only then, you can decide what diet is appropriate for you.

Without a further adieu, let me introduce three major body types…

  1. Endomorph (fast oxidizer with slow metabolism): rounder, curvier and have thick bone structure. 
  2. Mesomorph (efficient metabolism): athletic built, heavier on the bottom, medium built.  
  3. Ectomorph (slow oxidizer with fast metabolism): Thin, tall and small frame.

As unique as you are, you most likely won’t fit into one body type perfectly.

The point here is to find out which type you are closest to, so you can have an idea of your metabolism speed, oxidation rate, macronutrient needs and food intolerance/tolerance.


If you are an Endomorph, it’s important to slow down oxidation and speed up your metabolism, so you can avoid insulin spike and burn more calories.

In other words, your aim is to create a more efficient balance of available energy and energy going out, so you won’t have too much of excess your body needs to store. 

The way to achieve it is though eating and exercising.

For this body type, protein and fats are essential.

Your body does well and even appreciates protein foods like steak, chicken thighs, lobster and anchovies. They provide high purine protein to your body, and your body needs it.

What it needs the least is non-vegetable carbs such as grains and fruits. These food sources convert to energy fairly fast and often contain a high level of sugar, which can spike your insulin level.

You still need all three macronutrients (protein, fats and carbs), but eating in a way that optimizes and supports your body is the real secret to your weight loss and slim down.


If you are a mesomorph, you are blessed with efficient metabolism with mixed-type oxidation. Your focus is to burn fat a bit more efficiently by keeping a balanced meal. You need high-purine protein as well as low-purine protein, so you don’t tip over one side more than the other.

You can also enjoy a good variety of fruits and some grains but not too much.

Your aim is to avoid an unbalanced diet, which can put your efficient metabolism at risk.


If you are an ectomorph, your fast metabolism can keep you slim despite your efforts to stay thin and slender.

Your focus is not to slow down oxidation too much to avoid your body from sensing hunger and starvation, which can cause fat hoarding.

Your body tolerates carbs wells and even does fine with sweeter fruits.

You also need protein too, but less of it than endomorph and mesomorph women.

In a sense, ectomorph women do well with vegetarian type of diet or low-protein, low-fat diet, because those diets are closest to what your body needs and craves.

Making Dieting Work For You

Dieting is not about the method itself. It’s about matching your food choices closely to what your body needs and craves in the proportion it needs.

The further away your diets are from the needs of your body, the diet failure rate goes up. 

That’s why it doesn’t surprise me at all why some women lose all the weight and experience their optimal health with Paleo diet when others don’t see the same results.

It’s the same reason why some thrive in vegetarian and vegan diets and others feel sick eating that way.

Once you start feeding your body what it needs to improve and burn more, you can literally see your weight come off right in front of your very eyes.

It’s the fastest way to a healthier you and the best shortcut to the leaner, sexier sizzling body you always wanted. 

For more tips on how to eat for the body you want, check out our another recent post. 

For 7-Day Meal Plan, food list, and specific food compositions best suited for your body type, check out our new book, the 4-Week Bikini Body Express Plan. 

Misato Alexandre


After making healthy living a priority, Misato lost over 20 lbs in less than 90 days. Instead of weight loss being a dreading experience, living the lifestyle of health and fitness granted her more happiness and joy than ever before. She co-founded Fitwirr to make health and fitness simple for everyone and share her tips through writing evidence-based articles on nutrition, weight loss, and exercise.

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