Why you shouldn’t lose weight too quickly

“Drop two dress sizes by Christmas!” “Lose the festive bulge by NYE!” “Squeeze into your LBD with a two-week blitz!”

Nowadays we’re bombarded with supposed quick weight loss fixes, and this is the time of year when they peak.

To many, the prospect of dropping a dress size in a fortnight seems too good to resist - if you could slim down in time for a certain festive party in the near future, why wouldn’t you give it a try?

But crash diets are not good for your health and could lead to nutritional deficiencies, muscle loss and slower metabolism, according to leading Harley Street nutritionist Rhiannon Lambert.

What’s more, losing weight that quickly is not sustainable, and you’ll almost definitely end up regaining everything you lost - studies have proven this to be true.

When you crash diet, as the name suggests, you end up crashing and giving up. It’s not sustainable.

But if you lose fat gradually over time, you’ll develop skills for mindful eating, reset your habits, rebuild a healthy relationship with food and ultimately create a new balanced lifestyle for yourself.

“Increase fruit and vegetable intake, complex carbohydrates instead of simple carbohydrates, and decrease processed sugary foods,” suggests Lambert.

According to the NHS, a healthy amount of weight to lose per week is one to two pounds. However if you’re working out and doing a lot of muscle-building exercise too, you may not see the number on the scales drop despite that fact that you may be burning fat because you’re building muscle at the same time.

The reason you often put weight back on after crash dieting is because what you’ve lost isn’t really fat at all.

“Through these [crash] diets, fast weight loss can happen and usually more than two pounds can be lost in the first week,” Lambert, whose forthcoming book Re-Nourish: A Simple Way To Eat Well is released December 28, explained to The Independent.

“However, a lot of this ‘lost weight’ is actually water weight, which is due to the glycogen that is burnt for energy as the restricted diet is not bringing in enough energy for the body, so it has to use its stores.”

So that’s why you’ll end up putting the weight back on again.

Weight loss aside though, dropping pounds too rapidly can damage your health.

“When you decrease your calorie intake, nutritional deficiencies can arise as less food means that important nutrients such as mineral and vitamins are decreased,” Lambert says.

“However, along with the nutritional deficiency comes the effects of the deficiency. For example, a lack of Vitamin D, calcium and phosphorus can lead to weak and brittle bones. Additionally, fatigue and anaemia can arise due to minimal iron and Vitamin B12 in the diet.”

If you consume a varied diet, you can avoid this.

Most people want to lose fat when they think about losing weight, but with crash diets they often end up losing water and muscle.

“There’s a great deal of research demonstrating a low calorie diet often results in more muscle loss than a higher calorie diet,” Lambert explains. “In the long run though, you actually want to reduce fat and increase muscle, which can take a while to gain.”

Your metabolism determines the number of calories you burn per day and factors such as age, gender and genes can influence the speed of your metabolism. But losing weight too quickly can slow your metabolism meaning you burn fewer calories a day.

“This slowed metabolism can be due to a loss of muscle and a decrease in the thyroid hormone,” Lambert explains.

It may not make headlines, but at the end of the day, slow and steady fat loss is key to keeping the weight off and not regaining everything you tried so hard to lose.

“Losing weight too fast may give some quick results, but they can lead to a damaged body both mentally and physically,” Lambert says. “In the long run, the weight will most likely increase back to the set point.”

These products are typically rich in sugar and unhealthy fats that can increase body fat and may spike blood sugar levels leaving you hungry shortly after consumption.

Ensuring each meal time benefits from a balanced plate made up of protein, complex carbohydrates and healthy fats along with vegetables and fruit will set you with so many health benefits as well as keeping you fuller for longer and provide key energy.

Loss and lack of sleep can boost levels of ghrelin (the hunger hormone) and decrease secretion of leptin (the hormone that keeps you full). Therefore, lack of sleep can lead to significantly increased hunger.

Resistance training is widely considered to be great for growing muscle, and high intensity exercise very effective in burning calories during and long after any workout.