We all have a friend who’s hooked on the latest fad diets. Heck, maybe it’s YOU. So this comprehensive breakdown shows you why fad diets don’t work. Period.

Russ Howe PTI

This article was written by Russ Howe PTI, and was last updated on October 24th, 2023.

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What started as an idea as simple as “I’d like to lose a few pounds”, has festered in your head, and suddenly it’s all you can think about.

Now you’re one step away from trying Gwyneth Paltrow‘s goat milk detox.

I’ve been there.

So have many of my clients.

The good news is you don’t have to do a crazy fad diet to lose weight.

In fact, you’ll get better results if you avoid them.

The bad news is these things will always be ready to prey on your insecurities and take advantage of your naivety in exchange for your hard earned money.

So today I’m going to prepare you for the long battle ahead.

Here’s a step-by-step guide to show you why fad diets do not work, and why you shouldn’t waste your time (and energy) on them.

Why Fad Diets Exist

I’ve been fortunate to work in the fitness industry for nearly 20 years, and let me tell you something:

These things have always been there.

We’ve always wanted to know how to lose weight quickly.

And in today’s society, it’s probably worse than ever before.

I mean, if we want pizza we simply tap an app and then bosh, it’s at the door.

If we want to see what our ex has been up to, we no longer need to stalk them. We just jump on Facebook and bosh, turns out they gained 60lbs and started listening to Nickelback.

So it makes sense that, in a world where most of us are unhappy with the way we look, we get bombarded with promises of diets that can return instant results for very little effort.

But that doesn’t make them any less bulls**t than they were 20 years ago…

I’ll explain.

why fad diets don't work

Your Diet Versus Your Body

I’ve said this before, but if you’re new here, listen up:

The human body is the smartest machine either of us will ever operate.

It’s more high-tech than the latest iPhone. It destroys even the most expensive PC.


Tens of thousands of years into our existence, and we are still discovering new facts about it!

So the very notion that we can somehow ‘trick it’ is absurd.

Sadly, that’s the shaky foundation every fad diet is built upon.

These charlatans will happily tell you that your weight loss doesn’t come down to the laws of thermodynamics. Instead, it’s all about cutting sugar. Or grains. Or foods which start with a ‘C’…

And in our desperation, we often buy into it.

But it’s time to stop.

why fad diets don't work

Case Study

If you’ve ever tried a crash diet before, then the following story may sound familiar.

I had a pal try the latest celebrity diet from a women’s magazine, and the results were exactly as predicted.

The diet called for her to perform a “60 Day Shred” which was big on fruit juice and asked for a daily energy intake of 600 calories.

Her current intake was around 2800, so this was a massive drop.

After an initial weight loss period where she thought she’d stumbled across the holy grail, it all went to s**t and she actually gained weight.


And why does this happen to most people?

I broke this process down in more detail in this article, but in a nutshell our body responds to drastic calorie cuts by making metabolic adaptations that slow down weight loss.

It becomes more efficient on less fuel.

So while we may see an initial drop in weight (because it didn’t see the diet coming), this soon slows to a halt and we learn how to function on as little energy as possible.

Despite the fact that my pal was eating/drinking just 600 calories per day and pounding the treadmill hard every night after work, she couldn’t lose any more weight!

She was also suffering from a severe lack of energy, shuffling around her office like an extra from Z-Nation.

(Everyone knows a Z-Nation reference is cooler than a Walking Dead reference.)

Missing Micronutrients Everywhere…

One of the common problems with fad diets is they like to pin our previous failures on one thing.

So we get a bunch of diets which each have a pantomime villain apparently responsible for preventing you losing any weight in the past:

No carbs… no sugar… no dairy… no gluten… no fat, etc.

Some even go as far as to recommend eating only one single food (i.e. the cabbage soup diet).

Here’s the thing…

When entire food groups are removed from the menu, this leads to a very restricted list of choices which are given tags as “good” or “bad”.

It’s the start of a downward spiral.

I hate this approach, because it builds a very unhealthy relationship with food in the long-term. It’s like planting seeds for a future eating disorder.

Plus, research shows that we achieve far greater results when we stay away from such drastic methods and take a more relaxed, flexible approach. (1, 2)

There is no such thing as “good carbs” and “bad carbs”. There is only carbs.

Likewise, there’s no such thing as “good food” and “bad food”. There is only food.

Despite the hype, there is absolutely zero academic research to state any one single food will inherently make you fat. The only thing which will do that is eating too many calories. (3, 4)

Another issue which raises it’s ugly head is a lack of micronutrients.

By jumping into such a restricted food list, we inadvertently miss crucial vitamins and minerals in our diet.

These micronutrients play a key supporting role to our macronutrients (protein, carbohydrates, and fat), and are responsible for everything from our energy levels, to a better immune system, to even the strength of our hair and quality of our skin.

It’s why sailors used to catch scurvy by eating only fish and rice for months on end.

have i lost weight or water

Then There’s The Water…

Remember my pal who initially dropped a few pounds before hitting that “brick wall”?

Well, not all of that was weight loss.

A fair chunk (maybe more than half!) was good old water…

As you can see below, most fad diets are based around the concept of reducing carbohydrates as low as possible. This in turn causes the body to flush water from muscle cells, creating the illusion of instant weight loss.

It’s a sneaky tactic, but one which fools the trainee into thinking they’re losing actual body fat, when they’re not.

It’s why most fad diets are based around short timeframes (i.e. 30 Day Detox, 21 Day Fix, etc). This is just long enough for you to experience water weight loss, hit the wall, then headbutt your way into the fridge in sheer frustration.

The worst part?

When you crash off the wagon, these motherf**kers will make you think you’ve gained 10lbs overnight because of your weak will, when in fact the majority of that was simply regaining the water you lost!

(More carbs reintroduced = more water stored.)

As soon as you get back on the fad diet you will immediately flush that water once more, creating that illusion again, and they’ll pounce for a testimonial stating this new diet is the best thing since The Rock did this.

why fad diets don't work

A List Of Fad Diets That Don’t Work…

Now that you know how fad diets are full of s**t, and why you should avoid them at all costs, let’s take a look at some below.

These are fad diets which continue to remain popular and make a comeback every few years, despite a clear lack of evidence supporting their claims.

Maybe you’ve got a friend who’s been sucked into one…

… share this with them.

If they get offended, they can always fill out this form.

Let’s get stuck in. I’ll break down how the creators of the diet state it works, then show you precisely why they’re full of s**t.

dukan diet


Originally famous in France, this fad diet found popularity via celebrity magazines.

It is split into four phases.

During phase one, you are told to eat only protein (?!).

In phase two, this changes to protein and vegetables.

Phase three moves to protein, vegetables and starches, and phase four says you can eat whatever you want, providing you set aside one day per week as a protein-only day and “take the stairs whenever possible”.

What we see here is a zero carb diet, which changes to a low carb diet, and finishes off with some quite strange tips!

Why The Dukan Diet Doesn’t Work:

1. No calorie targets. Eat whatever you want “as long as you take the stairs”..?! There aren’t enough stairs in the world for the amount of cake I would eat under this advice.
2. Unsustainable long-term.
3. Very restrictive food choices, especially in the early stages.
4. Cutting food groups.
5. Missing key micronutrients via foods which are cut out.
6. Bulk of weight lost is simply water, due to zero/low carbohydrate intake.

fad diets that don't work


Ah, the HCG diet…

On a list of the most crazy diets I’ve ever seen, this one takes the top spot.

With the HCG diet, you will be eating 500-800 calories per day and taking injections of the pregnancy hormone, HCG.

Yeah, you read that correctly; f**king injections!

Once again, restrictions are placed on carbohydrate intake.

The OMG factor is raised even higher next, because if you slip off your diet you’re instructed to eat just 6 apples the next day to “make up for your mistake.”

You cheating b**ch…

There’s so much wrong here that it makes Herbalife look great.

HCG injections have been linked with blood clots, constipation, and headaches – and yet, oddly, the one thing it hasn’t been successfully associated with is f**king weight loss!

Why The HCG Diet Doesn’t Work:

1. No evidence to support the notion that HCG injections lead to weight loss.
2. Very unsustainable calorie target.
3. Metabolic adaptation will occur.
4. Restrictive food choices.
5. Missing key micronutrients.
6. Carbohydrate restriction leading to water weight loss.

the 17 day diet


Created by Dr. Mike Moreno, the 17 Day Diet is every bit as absurd as it sounds.

It’s based around the concept of changing your calorie and macronutrients every 17 days, because the author claims this will “confuse your metabolism”.

No studies exist to support this idea.

However, marketing buzz-phrases like “Activate your skinny gene!” promoted this to become a best-seller a few years back.

The idea is to walk for 17 minutes per day, and to stop eating carbohydrates after 2 O’ Clock in the afternoon. Like the Dukan Diet, it’s broke into four stages.

Except this time they have awesome sounding names; Accelerate, Activate, Achieve, Arrive!

Why 17 days?

Well, cuz magic.

But despite the fact it claims you can lose upto 12lbs in the first 17 days by “clearing your body of toxins that affect your metabolism”, it’s really because you’re flushing a f**k-tonne of water from your system.

As you move through each stage, you’re instructed to add carbohydrates slowly (sticking to the nonsense rule about needing to eat them before 2 P.M. to prevent it being stored as body fat), although no calorie targets are provided (?!) and by stage four you’re ready to commit to buying their handy list of 17 Day Diet supplements for the rest of your life.

Why The 17 Day Diet Does’t Work:

1. No calorie targets. You can eat as much as you want, but will apparently lose weight because… nope.
2. Once again we restrict carbohydrates, leading to initial water weight loss which the author claims is “toxins” leaving your body.
3. Missing micronutrients.
4. Bulls**t myth that we will store carbs as fat if eaten later in the day. This is simply not true.
5. Hooking the trainee in to a lifetime of buying supplements.

list of diets that don't work


Did you know you can lose upto 500 calories by having a conversation with someone who is following this diet?

That’s because their stinky meat breath will make you throw up.

The Atkins Diet was everywhere during the early 2000’s. What’s unique here is that it attracted a cult-like following, with people going bats**t crazy if they saw a starchy carb around them. This type of behaviour has since been replicated by those selling keto, paleo, etc.

Once again it’s based around cutting carbohydrates and promising “wooing the trainee with claims of “up to 15lbs weight loss in the first two weeks”…


You guessed it. Water.

Why The Atkins Diet Doesn’t Work:

1. Unsustainable in the long-term.
2. Primarily water weight loss, leading to an immediate weight regain when the trainee re-introduces carbohydrates to their diet.
3. Demonization of food groups is always a negative thing.
4. Heavily restricted food choices.
5. Missing key micronutrients.
6. You’ll never get a GF with that breath…

do crash diets work


We all have a guy at work who insists he’s “a hunter gatherer”.

Sure, Frank.

Hunting those chicken breasts in the aisles of Tesco isn’t quite how the cavemen did it, but go for it…

I do agree with certain aspects of this plan (more lean meat, more vegetables, more water), but as always, we take things too far.

Foodies (a.k.a. people who upload clean eating memes on Instagram to remind you they’re better than you) advise us that any food which is cooked is bad for us. We have to eat it raw, otherwise we’ll lose key nutrients.

Here’s the line:

And now we’ve just crossed it.

See, we went to Crazy Town again!

While certain vegetables do lose some nutrients in the cooking process, others require it in order to unlock their full potential. And then there’s protein…

… not only is it f**king disgusting to eat raw meat, allow me to confirm it’s also f**king pointless.

All this minutia is overruled by the fact that no diet should make you want to kill yourself. And this does.

Why The Raw Food Diet Doesn’t Work:

1. Very unsustainable due to constant food prep involved.
2. Very restrictive food choices.
3. Despite all the talk of superiority, we’re basically running a low carb diet and will lose water.
4. The most expensive option on the list, as everything needs to be fresh.

alkaline diet debunked


We all have a friend who talks about doing a detox, or a juice cleanse.

They’re prime candidates for The Alkaline Diet.

This plan is so anti-science it claims it can magically change the body’s pH levels. Apparently, all you need is some yoga pants, ice water with a slice of lemon, and a smug sense of superiority.

But here’s how it works…

Due to the severe restrictions placed on food choices, the bulk of your calories will have to come from fish, nuts, vegetables and seeds.

So, once again, we are running a low carb diet (= water weight loss) and when people are faced with a restrictive list of foods they typically eat lower calories due to sheer boredom.

Why The Alkaline Diet Doesn’t Work:

1. Very unsustainable.
2. Water weight loss is a major factor due to low carb intake.
3. The very name is bulls**t; we are not changing our body from acidic to alkaline. We’d literally die.
4. Restrictive list of food choices.
5. Missing micronutrients.
6. Large calorie reduction encouraging metabolic adaptation.

reasons why fad diets don't work


So, there you have it…

A comprehensive explanation of why fad diets don’t work; why none of my clients use them; and even a list of several of the most popular fad diets broken down and debunked before your very eyes.

I hope you’ve enjoyed this in-depth breakdown.

Share it with any of your pals who keep on getting sucked into these nonsense things!

Thanks for reading. If you’ve enjoyed yourself, jump on my email list for more training tips. You can now also download a workout app, stacked full of effective training plans that’ll kick your a**.


  1. Smith C. F., et al. Flexible vs. Rigid dieting strategies: relationship with adverse behavioral outcomes. Appetite. (1999)
  2. Stewart T. M., et al. Rigid vs. flexible dieting: association with eating disorder symptoms in nonobese women. Appetite. (2002)
  3. Karl J. P., et al. Substituting whole grains for refined grains in a 6-wk randomized trial favorably affects energy-balance metrics in healthy men and postmenopausal women. Am J Clin Nutr. (2017)
  4. Leibel R.L., et al. Energy intake required to maintain body weight is not affected by wide variation in diet composition. Am J Clin Nutr. (1992)

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I’m Russ. I’ve been a personal trainer since 2002, and I own russhowepti.com.

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