Carb cycling on a low-carb diet
A low-carb diet doesn’t have to mean endless tuna, workouts with nothing in the tank, and a bad mood. Carb cycling alternates low-carb and high-carb days so that fat burning, strength training, and recovery can support one another.
If you’ve been dieting for a couple of weeks, you’ll quickly recognize the signs. Reps get harder, you can’t stop thinking about spaghetti, and your motivation starts to crumble. This is where a plan that puts carbohydrates in the right place, rather than banning them forever, comes in.
Low-carb diets and the idea behind cycling
Carb cycling means varying your carbohydrate intake from day to day. On some days, you keep carbohydrates low and focus on fat burning. On others, you eat more carbohydrates, particularly around your workout, to help your muscles recover and replenish their glycogen stores.
The best-known stricter version is the cyclical ketogenic diet, or CKD. Dan Duchaine popularized it in the 90s with his book BodyOpus. The classic CKD model includes a five-day ketogenic phase: no carbohydrates, plenty of fat, and moderate protein. This usually runs from Monday to Friday. After a glycogen-depleting workout, 48 hours of carbohydrate loading follows.
The idea is simple. When muscle glycogen is low, the carbohydrates you eat during the loading phase are used more effectively to replenish muscle stores. If you also keep your fat intake in check, a high carbohydrate intake doesn’t automatically have to mean gaining fat.
Frankly, CKD isn’t for everyone. It requires strict control and may be too rigid for a beginner. A more practical option is a gentler cycle: one lower-carb day and one higher-carb training day.
Why does a low-carb diet alone leave you tired?
A conventional diet keeps your calorie intake low every day. This works if you can stay consistent, but your strength training may suffer. Your body doesn’t recover as well, the weights feel heavier, and you start wondering: do you have to sacrifice all your strength to get in shape for the beach?
A cyclical approach has two major advantages. First, you get carbohydrates when they’re most useful: around your workout and afterward. Second, it’s easier mentally. Knowing that a high-carb day is coming soon makes it easier to get through a day when your plate holds more protein and vegetables.
Things can get difficult when a carb-loading day becomes an excuse to eat unlimited amounts of everything. That’s not the point of the plan. Your carbohydrate intake may be high, but your calorie target and fat intake still matter.
How does a cyclical low-carb diet work?
Start by estimating your daily calorie expenditure—the intake at which your weight stays stable. Here’s a simple calculation: men multiply their body weight by 30-40, depending on activity level. Women multiply their body weight by 28-38.
For example, a 90 kg man with a low to moderate activity level could use the formula 90 x 33 = 2970 kcal. Rounded off, that means about 3000 kcal a day to maintain his weight.
Low-carb day
The aim of a low-carb day is effective fat burning. In this example, 700 kcal is subtracted from the maintenance intake of 3000 kcal. That leaves a daily intake of 2300 kcal.
| 2300 kcal | (-700 kcal) |
| 115 g carbohydrates | (20 % of 2300 kcal) |
| 345 g protein | (60 % of 2300 kcal) |
| 50 g fat | (20 % of 2300 kcal) |
For exercise, 45-60 minutes of aerobic training at low or moderate intensity is suitable. In this example, that burns about 300 kcal, bringing the total deficit to nearly 1000 calories.
Why so much protein? A higher protein intake during a diet helps preserve muscle mass and keeps you feeling fuller. Carbohydrates are low, but not forever. The next higher-carb day is already part of the plan.
High-carb day
The aim of a high-carb day is to make up for the deficit and support recovery. This day pairs well with strength training. In this example, you return to 3000 kcal—your maintenance calorie intake.
| 3000 kcal | (maintenance calorie intake) |
| 400 g carbohydrates | (60 %) |
| 180 g protein | (about 25 %, calculated as 2 x body weight in kg) |
| 50 g fat | (15 %) |
Across these two days, the average calorie deficit is -500 kcal per day. A deficit like this could produce weight loss of about 0.5 kg per week. The idea is not to starve yourself, but to make the lower- and higher-intake days work together so your training doesn’t fall apart.
Carbohydrate loading after your workout
It is worth starting carb loading straight after your workout. The original plan recommended getting 75 % of your daily carbohydrates in your post-workout meal. This supports recovery and glycogen storage when your body really needs those carbohydrates.
If you train in the evening, you can have two low-carb meals and one high-carb meal before your workout. For example, you might have 20 g, 20 g and 60 g of carbohydrates before training, then the remaining 300 grams of carbohydrates afterward. You do not need to get this exactly right. What matters is that you eat a large proportion of your carbohydrates after training and that your pre-workout meals allow you to put in a proper effort.
So what actually happens? Strength training helps keep energy expenditure elevated after your workout. This is known as EPOC. Still, keep your fat intake in check while carb loading: pushing both carbohydrates and fat very high quickly drives your calorie intake too high.
Be cautious with liquid carbohydrates, such as weight gainers and maltodextrin drinks. They make it easy to reach your carbohydrate target, but you lose one important benefit: a substantial post-workout meal that makes the diet mentally easier to follow. In terms of recovery, there is little difference between drinking maltodextrin half an hour after training and eating the same amount of carbohydrates in a pasta dish.
Training on a cyclical diet
The example uses a schedule in which you train every other day. Since high-carb days coincide with strength training, the number of workouts also affects your total deficit for the week. If you train four or more times a week, the deficit will be smaller.
When dieting, you do not need to pursue muscle growth at all costs. The primary goal is to burn fat and preserve muscle mass. Three to four workouts a week can produce fat loss of around 0.4-0.6 kilos per week. Training too frequently increases the risk of overtraining and may actually slow fat burning.
The number on the scale may not follow a straight line on a cyclical diet. As you lose fat and gain muscle mass, your weight may surprise you some weeks. This is especially common if you have less training experience.
What should you do in the gym?
Focus on compound exercises. Your program should include bench presses, squats, rows and pull-ups. You do not need a long list of exercises. It is better to put a solid effort into the movements you choose.
Do at least three sets per exercise and stick to 6-8 reps. For smaller muscle groups, such as the biceps, triceps and calves, two hard sets are often enough.
Your workout should last no longer than an hour. If it runs longer, you are doing too many exercises or your rest periods are turning into chat breaks.
A low-carb diet: practical choices
The aim of a high-carb day is to replenish muscle glycogen. Starchy foods that your body breaks down into glucose, such as pasta, potatoes and rice, are better suited to this. Sugar and fructose should not form the basis of your carb loading.
One enjoyable part of a high-carb day is getting to eat foods you can only dream of on a conventional diet. If you replace pasta, which is high in carbohydrates and low in fat, with ice cream, which has a moderate carbohydrate content and a moderate to high fat content, your proportions will shift away from the 60/25/15 model. If you stay within your calorie allowance, though, this will not immediately derail the plan.
On a low-carb day, your carbohydrates should come mainly from plant sources. This makes it easier to stay full. Chicken, tuna and lean meat are suitable protein sources.
The original plan also recommended fish oil during the diet. It linked omega 3 fats to a positive effect on insulin sensitivity, which may support carb loading. Six grams of fish oil a day is enough to have an effect.
After a couple of cycles, you can start assessing how your body responds. Some people need a little more food on high-carb days; others feel better with more modest carb loading. The simple truth is that you need a negative calorie balance by the end of the week if your goal is to burn fat.
The version presented produces a deficit of 7000 calories over two weeks. This means losing around half a kilo of fat mass per week. Exactly how you create that deficit is up to you. Just remember: the more you eat on a high-carb day, the less room you have on a low-carb day.
A low-carb diet: FAQ
Is a low-carb diet suitable for beginners?
A very strict CKD may not suit beginners because it requires tight control. A less strict cyclical approach that alternates lower-carb and higher-carb days is easier to follow.
Can you eat anything on a carb-loading day?
No. You can eat more carbohydrates, but your calorie and fat intake still matter. If a carb-loading day turns into uncontrolled eating, your weekly deficit will quickly disappear.
How many strength training workouts per week are sensible?
Three to four workouts a week is a sensible range while dieting. More workouts can work, but they reduce the deficit and increase the risk of recovery problems.
Translated from Body magazine; Author: Martin Berkhan
Author: Greta
Source: WHO – healthy eating.
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