Peta Bee lifts the lid on whether we should be following the bodybuilders and jumping on the back-loading bandwagon

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Becoming a lean machine with the supreme muscle tone of an A-lister has, until now, been fraught with compromise. Strict carb avoidance is, we’ve been informed, the holy grail of fat shredding, but anyone who has been there will tell you that as the blubber dissolves, so do your energy levels and, frankly, your zest for doing pretty much anything else.

While carb-phobia is rife at the moment, is it necessary? What if there was a route to leanness that involved the best of both worlds: fat loss via a diet that, at least at certain times, permits gorging on any carbs you fancy from pizza and chips to chocolate brownies and doughnuts?

As inconceivable as it sounds, carb manipulation or ‘back-loading’, popular for years among body builders, is enjoying a huge resurgence. And in a backlash against the high protein and fat brigade, thousands are following online diet plans that rejoice in the joys of not only including some sugars and starches for weight loss, but eating them at a time when we have long been told they do their worst: in the evening.

So what is going on? In a nutshell, the back-loading theory is that you avoid most carbs (vegetables are the exception) during the day, packing in only protein and fat. Scheduling your workout for late afternoon or early evening (and we are not talking a gentle yoga session or walk here, but HIIT , circuits or weight training), you are then permitted to eat carbs after you finish. It’s not a green light for indiscriminate stodge consumption, but advocates of the approach claim pretty much any carbohydrates are allowed, from the healthier end of the spectrum like sweet potato and brown rice to more refined, sugary foods such as white bread, cakes and pasta.

Consuming carbs in large amounts (particularly the sugary variety) is known to cause a spike in blood sugar levels. In turn, this triggers the release of the hormone insulin whose job it is to keep blood sugar levels stable. After intense workouts, the theory is that insulin grabs calories from carbs and transports them straight to muscle cells, where they are used up for repair and rebuilding as opposed to storing them as fat, which it might do at other times.

It’s the manipulation of this process that forms the basis of back-loading and a similar approach, Carb Nite, that advocates a 10-day low carb diet culminating in an evening of carb indulgence, popularised by US physician John Kiefer in his book the Carb Nite Solution, the bible of backloaders.

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Many leanness gurus agree that carbs have been unfairly maligned in recent years. In fact, they play a necessary role in boosting fat loss from the body when intense exercise is involved. Joe Wicks , the personal trainer and trained exercise scientist aka the Body Coach, is among those who are convinced carbs deserve their place in a healthy diet.

“Cutting down on certain food groups at the expense of others is just wrong,” Wicks says. "What you should be doing is balancing your macronutrients - that’s fats, carbohydrates and protein - exercising and eating things at the right time. Protein intake is always important for muscle growth, recovery and satiety. But when you have done a tough workout, you need a greater ratio of carbs to fuel your efforts.”

John Brewer, professor of applied sport science at St Mary’s University, Twickenham, says it’s unlikely that anyone could stick to backloading for very long. Neither would he recommend trying. “The theory is based on supposition rather than hard science,” Brewer says. “We do know that eating carbs after exercise enhances recovery, since this is the best way of replacing the stores of muscle glycogen that have been used for energy. But it’s certainly not a good idea to restrict carbs before a workout if you want to get the most of your exercise session.”

Whereas “most of us have sufficient stores of fat to provide energy for around 40 consecutive marathons”, our stores of carbohydrate in the form of glycogen are limited. “Ultimately the key to leanness is to use carbs to support high quality training and to increase the intensity and duration of that exercise progressively,” Brewer says. “Whatever diet fads say, leanness ultimately comes down to hard work and not overeating anything.”

So what’s the overall verdict? That body composition does not come down to favouring one food group over another and that, ultimately, you should eat like an athlete if you want to lower fat. And, thankfully, that means a bit of everything.

“I recommend clients who are doing a good training programme with weights and HIIT eat sweet potatoes, jasmine rice, rice noodles, quinoa and porridge oats along with the occasional white bagel,” says Wicks. “Combine these with good protein sources such as extra lean minced beef, turkey breast, chicken breast, cod and salmon and healthy fats like avocado, flax seeds, eggs and you won’t go hungry but will see a a dramatic change in your shape.”

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