Should you try carb back-loading?

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The Diet

Carb back-loading is a calorie and carb-cycling diet that lets you choose one of two goals: more muscle with minimal fat gain, or less fat with minimal muscle loss. It relies on timing your carb and calorie intake to make the most of anabolic (muscle-building) and fat-burning hormones – but the real headline-grabber is that it encourages eating junk food.

The Claim

The diet’s creator, John Kiefer, claims that by keeping carbohydrates and calories low but having very high-carb, high-calorie feeds in the evening after training, you can gain muscle and lose fat. High-GI (glycaemic index) carbs are preferred so that you get a short, sharp spike in insulin, replenishing muscle fuel stores and supporting muscle gain, but leave most of the day insulin-free so as not to inhibit your body’s fat-burning abilities.

The Method

The diet begins with an initial low-carb preparation phase, designed to increase your body’s ability to metabolise fat and help you work out how big your carb intake should be based on your fat loss.

Once on the diet, you eat sparingly during the day, sticking to lean protein and low-carb veg. On training days you have whey before training, and then in the evening you back-load with one or two large, high-GI, carb-heavy meals. On non-training days you keep the carb intake lower, with a smaller, lower-carb evening meal and more protein and healthy fats.

Try this carb back-loading meal plan

The Reality

Carb back-loading was, in a word, fun. I never felt hungry. The daytime diet of tuna salads and whey isolate shakes was familiar for me, but the back-loads were new territory. I felt like a ten-year-old again, consuming large amounts of ‘junk’ carbs such as cereal, pizza and pastries. Eating out was a dream, and I had to stop myself from training more often just to earn the ‘reward’ of the carb back-load afterwards.

One downside is that you have to train at around 5-6pm for optimal results, which is when gyms are busiest. You can train at other times, but the results – according to Kiefer – won’t be as good. The second problem was the carb intake. I’d calculated during the prep phase that I needed 450g of carbs, which equates to around 20 Krispy Kreme glazed doughnuts. Even when using carb drinks and junk food this was a challenge, and I often fell short.

The Results

I found carb back-loading easy to do, and eating only a couple of small low-carb meals in the day saved time and avoided a post-lunch dip in concentration. Although I was going to the gym having eaten very little, training felt good. My lift numbers went up, conditioning sessions were more intense and my recovery was great. My body composition testing, provided by Speedflex, showed a near 1kg rise in muscle mass and a slight loss of fat. Small changes in body composition are hard to track, but any lean mass gain with no change in body fat or even a little fat loss is a big bonus.

The real concern I felt each night was what all those doughnuts, pastries and bowls of Coco Pops were doing to my insides, but my health-oriented results were the biggest eye-opener – with my HDL or ‘good’ cholesterol levels rising, my LDL or ‘bad’ cholesterol levels falling, my triglyceride levels improving and visceral fat levels dropping.

The Verdict

Carb back-loading is a fun diet that could be a great choice for anyone looking to gain lean mass or drop fat. For the best results, though, you may have to rearrange your day.

Want more information? Read our Q&A with nutrition expert Scott Baptie 

Former columnist

Drew Price is a nutritionist and a former columnist for Men’s Fitness UK, which predated, and then shared a website with, Coach. He is the author of the The DODO Diet. He holds a masters degree in nutrition science from Western Sydney University, and holds certifications from the American College of Sports Medicine and the National Strength and Conditioning Association. In 2022, he is a doctoral researcher at Reading University.