Have you ever gained weight while training for a race or an endurance event and you want to know why it happens and how to prevent it the next time? That’s exactly what we’re going to dive into today.
This is something that comes up a lot, and I think it’s something worth addressing in a format where you can opt in or out of this conversation based on your own discretion and how you feel about weight loss or body recomposition discussions.
Typically I tend to avoid conversations around changing your body weight or fat loss—not because I’m against it (actually my PhD is in fat metabolism)—but because my training and everything I do is so performance-driven that I really focus on performance outcomes and goals. However, I also recognize that people have body composition goals and struggle with wanting effective, evidence-based, and smart practical ways to approach that.
Important Note: If this conversation isn’t for you, it’s okay to take a swift exit right now. I have tons of other content to dive into. I’d rather you get good information from someone like me who has a PhD in exercise physiology as well as fat metabolism and energy substrate use during exercise training than from some “cortisol hormone coach” making you afraid to ever train for an endurance event again.
When you are training for a race or an event, what I see a lot of people experience is they train for it and they either want to use it as a diet plan and expect fat loss because they’re training more, end up seeing that they don’t lose any weight at all, actually gain weight in the process, or maybe they lost weight the first time they trained for something but the next time they gain weight.
They feel really frustrated and say, “Well, the running or the endurance training alone is what made me fat,” or those are the things that “spiked my cortisol and made me hold onto belly fat” and all those claims people are making.
The Unfortunate Reality: It does come down to nutrition. Not cortisol, not running being “bad” for you—nutrition.
When you are training for a race—whether that’s your first half marathon, your first marathon, your first ultra, your first big endurance thing (big is relative to you and your fitness level)—you need to approach this with NOT the mindset of using it as a diet tool.
Key Principles:
My advice is going to be more in alignment with not how to lose weight while you’re training for a race or event. This doesn’t mean if you lose weight or recomp a little bit that that’s a bad thing—I know when I’m training for big races like ultramarathons, I do tend to lean out a little bit, but within normal parameters of my body weight fluctuations.
When you’re training for races and events, you need to start approaching them with a training diet fueling mindset, not a diet industry mindset applied to your training.
The Biggest Mistake: Most people take all the things they’ve learned about dieting or nutrition from a diet-focused, diet industry view and apply that to their training or racing. Then they don’t feel fueled, they’re spinning their wheels, they feel really hungry, or they don’t understand how to adjust either their food intake or macronutrients in a way that can help both support performance and mitigate some of that excess hunger.
That excess hunger tends to lead us to overeat, which tends to lead to increased body fat or gaining weight during training.
You need to first start thinking of yourself with a little bit more of an athletic view of nutrition and training and fueling. You need to start thinking: How do I eat to fuel my performance?
Eating to fuel your performance means eating enough—not undereating, not restricting, and not trying to white-knuckle your dieting approach while training for that race. That itself is going to lead to even more increased or inflated hunger than if you just ate enough and learned to mitigate or manage your hunger within that.
The first thing that I think so many people neglect when it comes to gaining weight, becoming “skinny fat,” or having poor body composition changes when training for a race or event is protein intake.
So many people make the mistake of not thinking they need moderate to high protein intake as a runner or endurance athlete because “that’s for the meatheads, that’s for the bros, that’s for the lifters.”
I’m Here to Tell You: The nutritional intake guidance and recommendation for people who do endurance training is pretty similar, if not sometimes more, than that of those who do strength training—especially if you do mixed training.
| Protein Recommendation | Details |
|---|---|
| Target range | 1.6 to 2.0 grams per kilogram of body weight per day |
| In pounds | Roughly 0.8 to 1.0 grams per pound of body weight per day |
| For higher body fat | Base on lean mass: ~1g per pound lean mass or 2g/kg lean mass |
| Per meal | 20-40 grams per meal (up to 50 for larger individuals) |
| Timing priority | Include protein especially at breakfast and around workouts |
Why Protein Matters for Runners:
Important note: One of the most classic models of muscle breakdown in exercise physiology research is eccentric downhill running. Running absolutely breaks down muscle, so we need protein to support repair and recovery.
A lot of people are afraid of carbs or think carbs are the boogeyman, that they should be keto, carnivore, or low-carb. At this point in time, the data for low-carb performance just isn’t there—it’s not supported. You’re going to do better with carbs.
Why Carbs Are Crucial:
| When Glycogen Is Low | When You Eat Enough Carbs |
|---|---|
| Your body pulls carbs from your bloodstream | You have adequate carbohydrate balance for your activity level |
| This makes your blood sugar low | You go into training sessions well-fed |
| Low blood sugar makes you “hangry” | You leave training not feeling hangry or low blood sugar |
| You get that uncontrolled hunger feeling | You can eat more responsibly in response to training |
| You want to “buy and eat everything” at the grocery store | You have normal hunger and satiety responses |
Key Insight: Endurance training depletes your muscle glycogen stores (your little carb stores in muscles) far more than resistance training does. A long enough or high enough intensity running session can 100% deplete your carbohydrate stores.
This doesn’t mean fats are bad—you should eat adequate fats in your diet from good fat sources. What I’m saying is that we need to be more strategic about fat intake when training for races.
The Mixed Macro Problem:
When people reach for foods they think are primarily carbohydrates—like mac and cheese, pasta dishes, muffins, pastries, donuts—these are actually mixed macros with a lot of fat in them. You don’t meet your carbohydrate needs, you eat more fat (which is calorically dense), you meet your calorie needs from fat intake, but you still don’t meet that carb need your body is looking for. Your body keeps sending hunger signals for carbs, and you end up eating more calories trying to satisfy the carb signal.
| Fat Intake Guideline | Details |
|---|---|
| Minimum threshold | Don’t go lower than 20% of dietary intake |
| My personal range | Rarely go under 25-30% of diet from fats |
| During race training | Bump up the ratio of carbohydrate to everything else |
| In off-season | Let fat intake go higher when carb needs are lower |
The Key: There’s a big difference in how you feel between 40% fat/40% carbs and 30% fat/50% carbs at the same caloric intake. My carb intake gets really high when training for races and events. In my off-season when I’m recovering or pulling back endurance volume, I let my fat intake go up higher within my caloric needs.
You have to increase your caloric intake as you increase training volume, but there’s a fine line here.
The Compensation Effect:
People who increase their training volume just a little bit at the lower end of the spectrum think they need a massive amount of calories, but you really don’t. There is some compensation that happens from your body—you end up moving less indirectly, you have less NEAT (non-exercise activity thermogenesis), less spontaneous physical activity, twitching, fidgeting. Your body conserves energy for recovery. The additive effect isn’t as much as you think.
But as you increase more and more training, there is going to be an additive effect. When I’m training for an ultramarathon, I eat somewhere like 400-1000 calories more per day in response to my training compared to my regular amount.
Strategic Calorie Cycling:
Don’t think: “I’m resting, so I should eat less”
Instead think: “I’m eating my normal amount on normal training days, but on higher volume days (long runs, double days, speed work), I need to bump up my caloric intake with a large portion coming from carbohydrates.”
This supports higher recovery needs and prevents that “ravenous crazy monster” feeling.
We cannot talk about maintaining body composition or that athletic, lean, toned look while running without saying: if you want to maintain that look while running or endurance training, you should be lifting while running.
Why Resistance Training Matters:
High protein intake paired with resistance training will do a lot for maintaining the body composition you’re looking for and helping reduce or prevent excess fat gain through the training process.
Don’t neglect food density, fiber, and volume from plants like vegetables and fruit. When your hunger is higher during training, you can’t just have a free-for-all eating whatever you want.
Build Meals With:
Why volume matters: When training, you’re digesting foods much more quickly. If you lived entirely on bagels, toast, and protein shakes, you’d be absolutely ravenous. You need filling meals with volume to stay satisfied between training sessions.
Balance: There will be times when you rely on smoothies, shakes, juices, and calorically dense, low-volume foods to meet your needs—that’s normal. But keep your main meals as filling, satisfying, well-made meals.
To recap, if you want to prevent unwanted weight gain while race training:
| Strategy | Implementation |
|---|---|
| 1. Eat adequate protein | 1.6-2.0g/kg body weight per day |
| 2. Include resistance training | Maintain muscle mass while running |
| 3. Eat enough carbs | Based on your activity levels and training demands |
| 4. Keep fats strategic | Within 20-30% of your nutrition composition |
| 5. Eat enough calories overall | Match your training goals without restriction |
| 6. Eat more on high volume days | Long runs, double days, speed work days |
| 7. Include fibrous plants and volume foods | Stay satisfied between training sessions |
This approach should help you feel better, perform better, and maintain the body composition you’re looking for while supporting your race training goals.
This Is NOT Advice to Be in an Energy Deficit:
This is to be at energy maintenance and meet the fluctuations of caloric needs as they change across the week in response to your training sessions. My intention with these conversations is never to say you should be restricting, undereating, or dieting while training for a marathon or race. The goal isn’t to be your thinnest, skinniest runner—it’s to fuel your performance appropriately while maintaining good body composition.
Sometimes we gain a little bit of weight while race training, and that can be normal within regular parameters of your body fluctuations. Training for a marathon shouldn’t have you gaining an incredible excess amount of weight, but a few pounds here and there might just be part of fueling for what you’re doing.
Resources to Support Your Race Training Nutrition:
Fuel your training appropriately, and the performance—and body composition—will follow.
I’m Exercise Physiologist, sports nutritionist, weight lifter, and ultra runner. I am here to bring science to your training in a no-nonsense way. I have helped thousands of women crush big lifting goals, cross race finish lines, and even do both. I’m here to help you do the same!
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