New studies show that cutting back on calories by dieting slows your body’s metabolism and makes it easier for it to lay down fat. So there’s no better reason to burn kilos with some outdoor exercise instead

If the festive period is likely to leave you reaching for trousers with an elasticated waist, and the New Year comes with a weight loss resolution, beware going on a diet to achieve your goals. New scientific studies reveal how a significant cut in your calorific intake can lead to post-diet weight gain.

While cutting back on calories does lead to initial weight loss, it also reduces your body’s energy expenditure, changes your muscle composition from fast to slow twitch, and makes it easier for your body to lay down fat when you resume a normal diet.

Research published in the American Journal of Clinical Nutrition tracked the body composition of 32 men over a six-week period. For the first week they ate 50% more than their energy needs, followed by three weeks at half their energy needs, and finished with a fortnight at 50% more than their energy needs.

The results showed that the period of half rations led to 6kgs of weight loss, but not all of this was fat. In fact their fat-free mass, which includes skeletal muscle, liver and kidneys decreased more sharply than fat.

The harsh diet also led to a significant reduction in resting energy expenditure of -266kcal/day, a 14% fall in heart rate and a 22% decline in the calories burnt when walking. Basically, this suggests that under reduced calorific dietary conditions the body closes down its calorie-burning functions to conserve energy, making it harder to lose weight.

These findings were echoed by a study conducted by Dutch scientists at the University of Maastricht and published in Nutrition & Metabolism.

This also found that the body adapts to energy restriction with a decrease in resting and exercise-induced energy expenditure, both during and after the diet.

After eight weeks on a low calorie diet, a trial group of 48 men and women’s total energy expenditure had slipped by an average of 17.5%, including a decline of 10.8% at rest and a massive 22.8% fall in activity-induced energy expenditure. Meanwhile, in the Frontiers of Physiology, researchers who semi-starved then re-fed rats found that fat storage accelerated after the period of restricted diet. In effect, muscles stopped burning as much energy.

“These energy-sparing effects persist during weight recovery and contribute to catch-up fat,” said the scientists.

So if you’re looking to drop a few pounds, the consensus suggests a better long-term strategy is to burn fat through exercise rather than diet your way to weight loss.

Daft dietsdieting

Often backed by celebrities, here are five of the craziest fad diets to gain traction last year, according to the British Dietetic Association. The UK’s largest organisation of food and nutrition professionals comes across a huge range of weird and wacky diets and diet claims, which can range from bad to downright dangerous.

Sian Porter, consultant dietician says: “Some people will believe almost anything and anyone when it comes to nutrition, food and diet.”

“The simple fact is, there is no ‘wonder diet’ just as there are no ‘super foods’ and no one diet fits all. What is super is the way many marketing machines coin certain phrases to make you think there is some magic wand approach to losing weight.

“Maybe it’s not as exciting but the truth is if you do want to lose some weight do it by eating a healthy, balanced diet that you can stick to, watch your portion sizes and be physically active. Think of it as a marathon approach to achieving your goals, as opposed to a sprint approach. Aim to make permanent changes to your diet and lifestyle that are sustainable for you in the long-term.”

No sugar diet

What’s it all about?
The Sugar Free Diet excludes all types of sugar and often carbohydrates.

BDA Verdict
Not such a sweet deal! Cutting down on free sugars, reducing the amount of sugar you add, and consuming fewer products containing added sugar is positive. However, some versions of the No Sugar Diet promote cutting out all sugar which is not only almost impossible, but would mean eliminating foods like vegetables, fruit, dairy, and nuts – leading to a less than healthy diet. Be aware that these plans can recommend just as sugary alternates such as maple syrup or honey, which is a huge contradiction.

The all-kale and chewing gum diet

What’s it all about?
All you can eat is kale salad and chewing gum.

BDA Verdict
Kale-amity! This diet is extreme, socially isolating, unbalanced, hard to sustain and potentially harmful. Many people get drawn in by so called super foods but no one food can provide all the nutrients you need. Nothing is wrong with kale, but if that is all you consume all day, every day, then problems will arise – it’s all about balance, a healthy relationship with food (not obsession) and variety.

Bulletproof diet

What’s it all about?
Foods are classified as “bulletproof”, “suspect” or “kryptonite” with rules on timing of meals.

BDA Verdict
Whilst the idea of minimising alcohol and processed food is positive, the classification of foods is at odds with health recommendations and lacks evidence. Time restricted eating is also at odds with many lifestyles. The Plan’s 400-calorie “bulletproof coffee” (containing e.g. 2tbsp of butter) does provide lots of energy but few nutrients. Better to go for foods with more nutritional content.

The super elixir

What’s it all about?
This is a food supplement aiming to change body tissue from an acidic to an alkaline state. The recommended dose is 2 teaspoons (or 10gs) per day. A month’s supply will set you back – brace yourself – £96 for 300g plus caddy/£62.50 for a 300g pouch.

BDA Verdict
How much? The benefits that this costly powder claims to provide can easily be obtained from fruit and vegetables and a balanced diet. Moreover our bodies are naturally capable of regulating acidity levels. Why not save between £750 and £1,152 per year, and spend it on some delicious fruit and vegetables and a “super” holiday instead!

Trim secrets

What’s it all about?
Trim Secrets is a pill, which claims to suppress appetite whilst boosting the metabolism, when combined with their 5 stage diet plan, which includes a balanced diet of 1,500 calories per day. Regular exercise and avoiding stress is also recommended.

BDA Verdict
By consuming 1,500 calories per day, most individuals should lose weight regardless of whether they are taking this pill. The pill has echoes of the grapefruit diet and includes guarana, which is high in caffeine. Beware of pills and potions and make sure you know exactly what you are buying and taking.

Main image: Shutterstock