Crash diets may work against you?

Crash diets have been around for years, but have stayed popular more recently thanks to influencers and social media. Typically, these diets involve drastically reducing calorie intake to 800-1200 calories a day for a few weeks at a time. Proponents of these diets claim they can lead to rapid weight loss, which may explain why they have such a significant appeal.

Indeed, research has shown these diets can be very effective for certain people. In a study of 278 adults with obesity, a 12-week crash diet of 810 calories a day led to greater weight loss after 12 months than people who reduced their calories only by portion control. The crash diet group lost an average of nearly 11kg (24lbs) versus 3kg (7lbs) in the moderate diet group.

Similarly, one study showed that very low-calorie diets may be beneficial for people with type-2 diabetes. The researchers found that 60% of participants who ate 600-800 calories a day for eight weeks were able to put their type-2 diabetes into remission. They also lost about 15kg (33lbs) on average. A follow-up at 12 weeks showed participants put about 3kg (7lbs) back on – but, importantly, their blood sugar levels remained similar.

But while these diets may lead to short-term weight loss success in some people, they can have the long-term consequence of damaging your metabolism. This may explain why about 80% of diets fail – with the person ultimately putting all the weight they lost back on, and even gaining more than they lost.

Crash diets and metabolism

Your metabolism is the sum of all chemical reactions in the body. It’s responsible for converting the food we eat into energy and storing any surplus energy as fat. Your metabolism is affected by many things, including diet, exercise and your hormones. Crash diets affect all these components.

With a crash diet, you consume far less food than normal. This means your body doesn’t need to use as much energy (calories) to digest and absorb the foods you’ve eaten. You also lose muscle. All these factors lower metabolic rate – meaning the body will burn fewer calories when not exercising.

In the short term, crash diets can lead to feelings of tiredness, which makes doing any activity (let alone a workout) challenging. This is because less energy is available – and what is available is prioritised for life-sustaining reactions.

In the long term, crash diets can change the hormone makeup of our bodies. They increase our stress hormones, such as cortisol. And over an extended period, typically months, high cortisol levels can encourage food cravings and cause our bodies to store more fat, (remember ‘STRESSED’ is ‘DESSERTS’ spelt in reverse).

Crash diets can also reduce levels of the hormone T3, which is produced by the thyroid gland. It’s critical in regulating our basal metabolic rate (the number of calories your body needs to sustain itself). Long-term changes in T3 levels can lead to hypothyroidism and weight gain.

Together, all these changes make the body more adept at putting on weight when you begin consuming more calories again. And these changes may exist for months, if not years.

Gradual dieting

If you’re trying to lose weight, the best strategy is to follow a long-term, gradual weight-loss diet and, ultimately, a personal review of your relationship with food. Don’t think of it as ‘Dieting’ but as a ‘Diet.’

“What food am I putting into my body that is truly nourishing my body?” Rather than the negative pattern of drastically restricting yourself as a quick fix. One that ultimately will prove to be a failed sticking plaster for weight control. Gradual diets have been shown to be more sustainable and have a less negative impact on your metabolic rate than crash diets. Gradual diets can also help maintain energy levels enough to exercise, which can help you lose weight.

The ideal diet is one that reduces body weight by about 0.5 to 1kg (1-2lbs) a week. This will prevent the body reacting with internal alarm bells. Preventing the body from battening down the hatches and, thus, making it harder to lose weight.

A final note. Consider the fact that weight gain is not because of an imbalance of calories but rather an imbalance of hormonal reactions to our lifestyle choices, including what we eat. A hormonal imbalance, not a calorie imbalance. That aside, the number of calories you’ll need to eat per day will depend on your starting weight and how physically active you are.

Extracts taken from Christopher Gaffney from https://theconversation.com and https://www.nzherald.co.nz