If you lift and run, food has a small identity problem. In the weight room you learned: protein, protein, protein. In the running world they say: carbs are your fuel. And if you do both, sooner or later you’re sitting in front of a plate of chicken breast and three broccoli florets, wondering why tomorrow morning’s intervals feel like wading through mud.
The answer isn’t to pick one of the two worlds. The answer is to feed both, at the moment they need it. This article shows what sports nutrition research says about it and how to put it into practice in everyday life.
Why you need to eat differently when you do both
Strength and endurance training add up in energy expenditure. That sounds trivial, but it has a consequence that’s often overlooked: the gap between what you “normally” eat and what you actually need grows with every session.
Sports nutrition describes this with the term energy availability: energy intake minus training expenditure, relative to fat-free mass. What’s left is the energy your body has after training for recovery, immune system, hormones and bones.
The 2016 joint position statement of the American College of Sports Medicine and two dietetics associations gives this as a guide: around 45 kcal per kilo of fat-free mass per day was associated with energy balance and good health, and a chronic reduction below 30 kcal with impairments. The 2023 consensus of the International Olympic Committee stresses, however, that these values aren’t a rigid cut-off for everyone, because people and body systems respond very differently. And the data come mostly from elite sport.
When training a lot meets dieting
If you train a lot and eat little at the same time, you can slide into a lasting energy deficit. The IOC calls it REDs, Relative Energy Deficiency in Sport: a syndrome that impairs physical and mental functions, explicitly in women and men.
Warning signs can include:
- performance stalls or drops despite training
- persistent fatigue, frequent infections
- recurring injuries
- menstrual disturbances or missed periods
- loss of libido, irritability, constantly thinking about food
If several of these come together, it’s a case for a medical check-up, not a discipline problem.
Carbs by training day
The most important lever when you lift and run isn’t the amount of protein, it’s how many carbs you eat on which day. The 2016 guideline distinguishes four load levels, in grams per kilo of body weight per day:
- Light (low intensity, technique): 3–5 g
- Moderate (around 1 hour of training): 5–7 g
- Hard (1–3 hours of endurance, moderate to high): 6–10 g
- Very high (4–5 hours a day): 8–12 g
The principle behind it was described by Impey’s research group in 2018 as “fuel for the work required”: carb intake is adjusted to the demands of the upcoming session, day by day and meal by meal.
A chef would say: you season the dish you’re cooking right now. The rest day gets a small portion of rice, the double day a big one. Protein stays constant.
And what about losing weight?
Energy balance decides fat loss, not a single bread roll. If you want to lose weight and train well at the same time, put the deficit on the light days and fuel the hard days properly. That way the quality of your important sessions is preserved.
Training fasted: yes or no?
Training with few carbs, called “train low” in research, amplifies adaptation signals in the muscle cell. In the review by Impey and colleagues, that was the case in around 73 % of studies. But only 37 % showed better performance. So an easy run before breakfast is perfectly fine. Intervals or heavy mixed sessions need fuel.
Two sessions in one day
For many people with a job who lift and run, the double day is reality: running or rowing in the morning, strength in the evening. This is exactly where the most common mistake happens: hardly anything is eaten after the first session, and in the evening the energy is missing.
For less than eight hours between two sessions, the guideline recommends:
1–1.2 g of carbs per kg of body weight per hour in the first four hours after the first session
15–25 g of protein (or 0.25–0.3 g/kg) in the first two hours
At 75 kilos, that’s about 75 grams of carbs per hour. That’s a proper meal, not a bar.
Important: this recommendation comes mainly from endurance research. After a short strength session, the need is smaller. There are hardly any studies specifically on mixed strength-and-endurance days.
Before, during and after training
Before: for sessions of about an hour or more, the guideline gives 1–4 g of carbs per kg, 1–4 hours beforehand. The closer to training, the smaller and easier to digest. A normal meal three or four hours before, a snack like a banana or bread with honey one or two hours before.
During: for sessions up to about 75 minutes, small amounts or a mouth rinse are enough. For one to two and a half hours, 30–60 g of carbs per hour; beyond that, up to 90 g.
After: the famous 30-minute window is overstated. Aragon and Schoenfeld showed in 2013 that its importance depends heavily on context, above all on when you last ate. What counts is the total over the day. The exception is the double day.
Protein: the constant
For athletes, the guideline gives 1.2–2.0 g of protein per kg of body weight per day, more with intense training or in a calorie deficit. In a large meta-analysis on strength training (Morton et al., 2018), the added effect on fat-free mass levelled off at around 1.6 g/kg. For most people who lift and run, that’s a good target, spread across three to five meals.
The rule of thumb: protein is the constant, carbs are the dial.
Fluids and caffeine
Fluids: from about 2 % body weight lost through sweat, performance can suffer; at 3–5 %, endurance performance typically does. Because sweat rates are highly individual, a test makes more sense than a litre figure: weigh yourself before and after a typical session. If you regularly lose more than 2 %, drink more during training.
Caffeine: according to the International Society of Sports Nutrition’s position stand (2021), caffeine consistently improved performance at 3–6 mg per kg of body weight, usually about 60 minutes beforehand. Endurance benefits most clearly. Very high doses around 9 mg/kg were often accompanied by side effects. At 75 kg, 3 mg/kg is about 225 mg, roughly two to three cups of filter coffee, although the content varies a lot.
Meal prep like a professional kitchen
The best knowledge is useless if there’s nothing in the fridge at 12:30 on a Wednesday. In a professional kitchen, the solution is called mise en place: everything in its place before service starts.
Applied to your training week:
1. On Sunday, mark your training days: light, medium, hard.
2. A kit instead of finished dishes: two carb bases (e.g. rice, oven potatoes), two protein sources (e.g. chicken, lentils or tofu), two vegetables, one or two sauces.
3. Cook neutrally, season when plating: that way the same ingredients become different dishes, and Thursday’s box still tastes good.
4. Portion by type of day: more carbs on hard days.
5. Double-day box: a refuelling meal and a snack for before the second session.
Bottom line
Eating for strength and endurance isn’t a diet plan, it’s a system: carbs by training day, protein as the constant, targeted refuelling on double days, fluids by test rather than rule of thumb, and a meal prep kit that carries the week. Most guidelines come from elite sport; applying them to amateur athletes is a sensible but not specifically tested inference.
The fuelling plan with carb table, double-day schedule and meal prep kit is free via Instagram (in German): comment TANKEN under one of the reels.
Medical note: this article doesn’t replace medical or dietetic advice. If you notice signs of energy deficiency, or if you have an eating disorder, diabetes, kidney or cardiovascular disease, or are pregnant, please seek medical advice.
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