ABC diet: how to lose or gain weight
The ABC diet is a simple calorie cycling system that helps you either lose weight from fat or add muscle mass — while always keeping your protein intake adequate. The system is built on three eating days (A, B and C), where you change the amount of carbohydrates but keep protein steady.
What the ABC diet is and how it works
The first step is to work out your average daily calorie intake. Add up all the calories you eat over a week and divide by seven. The number you get is the amount of calories you can eat on day B — it is the starting point of the system. To keep things simple, let’s look at an example of 3000 cal a day.
Fat: up to 15% of your calories
Only up to 15% of your daily calories may come from fat. At 3000 cal, that means up to 450 cal from fat. Since 1 g of fat contains about 9 cal, that gives you up to 50 g of fat a day. This fat should come from protein-rich foods — meat, chicken, supplements. Once fat is accounted for, 2550 cal are left for carbohydrates and protein.
Protein: the foundation of muscle mass
Most experts agree that for every 450 g of muscle mass you want to maintain, the body needs 1 g of protein a day — that is, over 2 g of protein per 1 kg of body weight. If you weigh 100 kg, you need at least 220 g of protein a day. Since 1 g of protein contains about 4 cal, protein accounts for roughly 880 cal. 2550 − 880 = 1670 cal are left for carbohydrates.
Carbohydrates: your energy reserve
1 g of carbohydrate also contains about 4 cal. Dividing the remaining 1670 cal by four, we find that you can allow yourself 417 g of carbohydrates a day.
Summary of a B day at 3000 cal: 417 g of carbohydrates, 220 g of protein and 50 g of fat.
The ABC diet for weight loss
Once you’ve set your B-day amounts, add aerobic training load to your training: 3 times a week for 30 min at a time, four weeks in a row. After those four weeks, start varying your calorie intake from day to day.
On day A, eat 30% fewer calories than on day B; the next day, eat as you would on a normal B day; and on day C, increase your calories by 20% — but not at the expense of protein.
- Day A: 290 g of carbohydrates and 220 g of protein
- Day B: 417 g of carbohydrates and 220 g of protein
- Day C: 500 g of carbohydrates and 220 g of protein
Why does this work? First, when your calorie intake drops, the body automatically starts using body fat as fuel. Second, alternating calorie amounts forces the body to burn more fat than usual. The benefit of the ABC diet is that the weight you lose comes from fat — your muscle mass is preserved.
The ABC diet for weight gain
The same system works in reverse. If you want to gain weight, use day A as your starting day (the former B day). On day B, eat 20% more carbohydrates than on day A, and on day C, increase your carbohydrates by 50% compared with day A. The amount of protein stays the same.
An example meal plan for a 100 kg man:
- Day A: 417 g of carbohydrates and 220 g of protein
- Day B: 500 g of carbohydrates and 220 g of protein
- Day C: 625 g of carbohydrates and 220 g of protein
Also take into account the minimal amounts of fat that come with your everyday meals.
ABC diet FAQ
Is the ABC diet suitable for a beginner?
Yes, but for the first four weeks it’s worth eating steadily at the B-day amounts, with no calorie fluctuations. That way your body adapts before you start varying the days.
How long until you see results?
You’ll usually see the first changes within 4–6 weeks, provided you stick to the calorie amounts and keep up the aerobic training load 3 times a week for 30 min.
Can the amount of protein be changed?
No. The whole point of the system is to keep protein constant — it protects your muscle mass both when you’re losing weight and when you’re gaining it. Only the carbohydrates change.
Author: Text by Cris Aceto from Flex, translated by Ero Viik
Source: WHO – healthy eating.
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