Fast diet, fad diet

A young women is on her phone outdoors about to call the police after being burgled.

Being burgled has a big emotional cost too.

Although you could be fooled into thinking that crash and fad diets will give you a quick fix solution, be careful how you treat your body. There’s a wide variety of quick diets out there, but losing weight too fast can be damaging for your health. Studies have shown that slower weight loss over a longer period is not only healthier than trying to create a massive calorie deficit every day, but also more likely to help you keep the weight off long term. Read on as we explain why it’s best to avoid fad diets that appear to work fast.

How do crash diets work?

Shocking your body with a short term low-energy food regime often appears to be working after just a few days. There’s a rapid weight loss, making it look like the plan is working. At this point, you haven’t actually lost any fat; all that’s happened is that you’ve used up the body’s limited store of glycogen, a form of carbohydrate. As you use up the glycogen, your body loses water with it, so you appear to be losing weight very quickly.

Why fad diets that work fast don’t really work

It turns out fad diets that work fast don’t actually work so well:

  • Crash dieting tends to make dieters tired, irritable, and lethargic, and brings on food cravings.
  • There are no ‘special combinations’ of certain foods (e.g. cabbage and watercress soup) that will boost your metabolism enough to help you lose weight. If you have a larger body type, you’ll actually have a higher metabolism than someone with a smaller body type anyway, simply because you have a heavier mass of body tissues.

Health risks of quick diets

  • You are at risk of not getting enough vitamins and minerals to stay healthy if you severely restrict your food intake with some kind of quick diet.
  • After using up your glycogen, you will start losing weight from your body’s tissues, as your body frees up energy to keep you going. Crash diets do this too quickly to be healthy.
  • What many diet plans do not tell you is that you are using up protein (e.g. from your muscles) as much as you are using up fat.
  • Even if you don’t give a monkey’s about being healthy and just want results, it’s important to realise fast weight loss can just as easily be put back on.

Yo-yo dieting

  • Weight often goes back on as fat, leaving you with more fat and less protein than you started off with, which can start off a vicious circle of yo-yo dieting.
  • Yo-yo dieting messes up your metabolism, and may even raise the levels of harmful cholesterol in the blood, increasing your risk of arterial disease and heart problems.

Check out our article on how to have a healthy relationship with food here.

How to spot dodgy fad diets

It seems as though there’s a new miracle diet book published every week. We all know someone who is doing one. It’s big business, with everybody looking for the magic answer that will make them slim and attractive. However, many of these diets are useless and/or downright dangerous.

  • A report by the experts at Which magazine earlier this year condemned a number of fad diets, including low-carbohydrate diets, cabbage soup diets and the ‘eat fat, get thin’ diet where the author actually stated that exercise is not important (yeah, right).
  • Many fad diets involve illogical rules that make it too difficult to eat many different foods. A side effect of this is that it prevents you from eating a wide range of foods, and variety is essential for good health. See our article explaining what a balanced diet is to learn more.
  • Beware of claims and theories that appear scientific, but have no scientific studies to back them up. Testimony from a famous person is just not good enough.
  • Moderately reduced-fat diets are often OK, but avoid super-low-fat ones. Your body still needs to take in a few essential fatty acids with your food.
  • Low-carbohydrate and high-protein plans such as the keto diet are potentially dangerous. These diets often contain too much saturated fat and not enough fibre, and a lack of carbohydrate can put the body into ketosis. Ketosis is an abnormal metabolic state with unpleasant side effects such as bad breath and nausea. The diet can also place a strain on the kidneys as well as causing low blood pressure, kidney stones, constipation, nutrient deficiencies and an increased risk of heart disease… not good stuff!
  • There is no evidence to support the theory that you should avoid eating carbohydrates and proteins at the same meal.
  • There is no proof that you need a special diet to go with your blood type. A small serving of a low calorie food (such as kidney beans) cannot make you gain weight — it just isn’t scientifically possible.
  • Detox diets are supposed to rid the body of ‘impurities’. Nobody has ever been able to say what these supposed impurities actually are. Although detox diets often claim to get rid of cellulite, it’s important to realise that cellulite is perfectly natural and…body fat isn’t a disease!

The best way to get down to your healthy weight

Here’s the bit nobody wants to hear. The best way to get down to your healthy weight and feel and look your best is to do it slowly. A balanced diet based on moderate calorie restriction and moderate regular physical activity will gently get you toned up, and keep the weight off for good. Read our guide to how to get fit here.

How to lose weight sustainably

To work out how many calories you should be aiming for if you want to lose weight sustainably, aim for a daily calorie intake falling between the amount required to sustain your BMR (Basal Metabolic Rate, i.e. how many calories you’d burn if you just did nothing all day, which you can work out with this calculator) and the amount needed to maintain your current body weight.

So, good luck, don’t forget to eat your fruits and vegetables! 

Learning to love yourself

It’s easy to get carried away with all the talk of diets, weight loss and the endless stream of half naked bods on social media. The reality is, learning to love yourself for who you are is much healthier than chasing an unrealistic body image you’ve seen online. Read body positivity guru Megan Crabbe’s story of learning to love her body here.

Next Steps


diet| weight

By Ally Thomas

Updated on 19-Oct-2022