Ketogenic diet and carbohydrate loading
A ketogenic diet gives you a strong base for fat burning, but in full ketosis you can’t sustain intense strength training. Muscles rely mainly on carbohydrates to lift heavy weights — ketone bodies and free fatty acids don’t deliver energy there. That’s what cyclical carbohydrate loading is for: 5 days of keto, 2 days of reloading, and then back into ketosis.
This article spells out exactly what to do on a loading day — how much, when, with which foods and with what kind of training. It is based on Lyle McDonald’s material “Carbing Up on the Cyclical Ketogenic Diet” and a comparison of the well-known approaches of Dan Duchaine (“Bodyopus”) and Mauro Di Pasquale (“The Anabolic Diet”).
Why a ketogenic diet needs loading days
A prolonged carbohydrate deficit lowers performance in strength training and can lead to loss of muscle mass. When glycogen stores run empty, both the weight on the bar and recovery between two workouts suffer. That is why periodic loading has to be built into the keto cycle — muscles recover, glycogen is supercompensated and the next 5-day ketosis cycle gets a strong start.
The two well-known approaches differ in the books. Di Pasquale recommends unstructured loading: after depletion you eat plenty of carbohydrates and then adjust based on how you feel and how your muscles look. Duchaine’s Bodyopus is meticulously precise — 48 hours, meals every 2.5 hours, even getting up in the middle of the night. In practice, a sensible compromise for most people is controlled timing without the night-time wake-ups.
Ketogenic diet: loading duration and amounts
Glycogen resynthesis is limited by enzyme activity — almost no matter how much you eat, the body can resynthesize only a set amount within a given time. Cramming the whole day’s loading amount into 4 hours simply doesn’t work.
- After maximal depletion, the body can restore normal glycogen stores (100–110 mmol/kg) 100% within 24 hours.
- To do that, you need to consume 8–10 g of carbohydrates per 1 kg of fat-free body weight in the first 24 hours.
- Within 36 hours, under ideal conditions, 150% supercompensation is reached — 150–160 mmol/kg of glycogen in the muscles.
- Even greater supercompensation (175 mmol/kg) takes 3–4 days, but it also requires light physical activity, which stimulates the muscles to “soak up” glycogen.
The first 6 hours after a depletion workout are the most decisive — enzyme activity is at its peak, about 12 mmol/kg/hour. In a study where 1.5 g of carbohydrates per 1 kg of fat-free mass was consumed immediately after strength training (the same amount again 2 hours later), 44 mmol/kg had been resynthesized by the 6-hour mark.
The resynthesis rate over the first 24 hours falls in the range of 5–12 mmol/kg/hour and depends on the preceding training. Aerobic exercise has a modest effect (2–8 mmol/kg/hour), strength training a medium one (1.3–11 mmol/kg/hour), while sprint training has the greatest impact (15–33.6 mmol/kg/hour). The reason strength training falls short of sprinting here is the greater amount of lactate and damage to muscle fibers.
At an average rate of 5 mmol/kg/hour, about 120 mmol/kg of glycogen is resynthesized in 24 hours. The same result is achieved by consuming 50 grams of carbohydrates every 2 hours — a larger amount no longer raises that rate. That adds up to 600 g of carbohydrates, the maximum worth consuming in the first 24 hours. These calculations apply to a man of about 70 kg; heavier people need proportionally more. The guideline is 8–10 g/kg of fat-free mass.
From the 25th hour the resynthesis rate drops, and the amount should be reduced to about 5 g/kg of fat-free mass. Overloading gives you “watery” muscles and switches on fat-storing mechanisms. In most people, the bulk of supercompensation happens within the first 24 hours, so the hours that follow need to be more restrained.
Which carbohydrates to eat and how often
The type of carbohydrate affects the resynthesis rate. In the first 24 hours, when enzymes are active and muscles are hungry, higher-glycemic-index foods are suitable: roughly 50% simple carbohydrates and 50% starchy complex carbohydrates. In the second 24 hours the emphasis should shift clearly toward complex carbohydrates and foods richer in dietary fiber — this keeps insulin levels steadier and lowers the risk of fat storage.
On timing, the studies are divided. In one study, participants did a maximal depletion and then consumed 525 g of carbohydrates — one group in 2 meals, the other in 7 meals. The glycogen resynthesis result was identical. In practice, though, smaller amounts are easier to digest and keep blood sugar stable, so splitting your intake into 4–6 meals a day makes sense.
Bodyopus recommends getting up at night and loading every couple of hours. Most bodybuilders see no point in this — anyone who loads only during waking hours achieves the same supercompensation. One middle-ground solution: have the amount that would otherwise be spread across the night before you go to bed. If you plan on 50 g every 2 hours, then for 8 hours of sleep that comes to 200 g before bed. If you eat it together with protein, fat and dietary fiber, digestion slows down and blood sugar holds steady through the night.
Depletion workout before loading
Loading should begin right after the last depletion workout. Even a 2-hour delay after training slows glycogen resynthesis by 47%. Ideally, right after the workout, take in 1.5 g/kg of carbohydrates in liquid form and 0.5 g/kg of protein per kilogram of lean body mass. You get an extra boost if you also eat carbohydrates 1–2 hours before the final depletion workout: insulin levels rise and the loading that follows gets going faster.
The final depletion workout should work all the major muscles. Bodybuilders have also had good results with a regular split, but a full-body workout is more effective from the standpoint of supercompensation. One important nuance: eccentric training (negative repetitions) is not suitable for the depletion workout. After three-day loading, the supercompensated glycogen stores of muscles trained in eccentric mode are 25% lower than with regular training. If you use 1–2-day loading, the effect may not yet show up; with 3-day loading, keep the eccentric emphasis out of it.
Protein and fat during loading on a ketogenic diet
If the amount of carbohydrates is sufficient for supercompensation, protein and fat do not affect it separately. In practice, though, fat causes a problem in another way: if the share of fat is too high, it suppresses your appetite and you can no longer eat the required amount of carbohydrates.
Realistic proportions for the first 24 hours are as follows:
- Carbohydrates: 8–10 g/kg of lean mass, providing about 70% of total calories.
- Protein: about 2–2.2 g/kg of body weight, making up about 15% of calories.
- Fat: about 15% of calories, and definitely under 85–90 grams.
15% protein seems too little to many people, but because total calorie intake is high on this day, the absolute amount is sufficient. Studies also show that a high share of carbohydrates relative to protein may raise testosterone levels. It is important to eat carbohydrates together with protein, as this promotes glycogen resynthesis, especially right after the final depletion workout.
During the second 24 hours the pattern changes: 5 g/kg of lean mass in carbohydrates (about 60% of calories), about 25% protein, and fat has to be cut by another half.
Does fat get stored during a ketogenic diet?
It’s a logical concern: doesn’t such a large amount of carbohydrates and calories undo the whole previous week’s work? The answer is no, provided you follow the guidelines.
In one study, the subjects spent 5 days on a low-carbohydrate diet and depleted their glycogen further with training. After that they ate 500 g of carbohydrates, split into three meals. The result: even 24 hours after loading began, the body was still in negative fat balance, meaning fat burning continued. The reason is simple. When glycogen stores are empty, incoming carbohydrates are directed to the muscles and liver, and fat keeps being burned for energy.
Another study, however, loaded with very large amounts: 700–900 g of carbohydrates a day, 5 days in a row. In the first 24 hours the subjects ate 700 g of carbohydrates and 60 g of fat, and only 7 g of fat was gained. In the second 24 hours they ate 800 g of carbohydrates and 97 g of fat, and this time as much as 127 g of fat was stored. By then the glycogen stores were full and the body had switched out of fat-burning mode.
The conclusion is clear: if you keep fat under 90 grams on the first loading day and carbohydrates at 5 g/kg on the second day, the risk of fat storage is minimal. Anyone who wants to bring the risk all the way down to zero should limit the loading period to 24 hours.
How long does supercompensation last?
This is a practically important question when timing your competition form. Under normal conditions, without hard training, the body holds on to its glycogen stores for about three days. The supercompensated state lasts just as long: three days. Keep this in mind if you are planning to load before an important competition or photo shoot.
Practical tips and a worked example
Many bodybuilders load purely by intuition: they eat tons of carbohydrates, a bit of protein and some extra fat, and hope for the best. That’s the classic two steps forward, one back. Structure helps.
- Keep loading short. During the first 24 hours the body stays in fat-burning mode. Loading for less than 24 hours causes no fat storage at all. Some people even experiment with two 24-hour loads a week (for example on Wednesday and Sunday).
- Structured loading, not a meal orgy. The keto diet tempts precisely with the idea that you can eat “everything” on the weekend. Constantly eating fatty foods on loading days ruins fat burning in the longer run. Start with foods with a higher glycemic index and move toward foods with a lower index and more dietary fiber.
- Keep an eye on the proportions of the other nutrients too. It’s tedious but necessary, to avoid overloading and fat storage.
- Consider supplements. HCA (hydroxycitric acid) 750–1000 mg 3 times a day, about 30 min before meals, reduces the risk of fat storage from overloading, according to practical experience, and keeps appetite in check. ALA (alpha-lipoic acid) 200–600 mg a day is an antioxidant and raises insulin sensitivity. Many bodybuilders consider it more effective than chromium and vanadium.
A worked example for 80 kg of lean body mass:
- Carbohydrates: 10 g × 80 kg = 800 g = 3200 kcal
- 3200 kcal makes up 70% of total calories
- Total calories: (3200 × 100) / 70 = 4571 kcal
- Protein: 15% × 4571 = 686 kcal = 171 g
- Fat: 15% × 4571 = 686 kcal = 76 g
These are guidelines. Everyone has to get to know their own body and find the optimal amount and duration for themselves — some people do well with a 24-hour load, others with 36 or 48 hours. The general principle stays the same: enough carbohydrates to replenish glycogen without storing extra fat.
FAQ: ketogenic diet and carbohydrate loading
Does a ketogenic diet necessarily need loading days?
If you only do low-intensity cardio training, you may get by without them. But a strength trainee who wants to preserve muscle mass will struggle without carbohydrate loading — performance drops and muscle mass is lost. A cyclical approach (5 days of keto + 2 days of loading) is a practical solution.
Exactly how many carbohydrates should you eat on a loading day?
In the first 24 hours, 8–10 g per 1 kg of lean body mass. In the second 24 hours, 5 g/kg. This assumes that depletion has been complete and that the last workout was done right before loading.
Do you have to get up in the night to load?
No. Practical experience shows that the supercompensation of those who load only while awake is no worse than that of those who also eat during the night. One solution is to consume the night’s share (for example, 200 g) before going to bed, together with protein, fat and dietary fiber.
Source: “Carbing Up on the Cyclical Ketogenic Diet”, Lyle McDonald, CSCS.
Translated by Janar Rückenberg
Source: WHO – healthy eating.
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