Dear Clients: Please Stop Trying to Run a Marathon and Lose Weight at The Same Time – Nutrition Awareness

(We’re begging you).

Why Running a Marathon Is Not the Best Way to Lose Weight

It’s such a common goal… wanting to lose weight, tone up, be more fit. Most of my clients have some kind of aesthetic-related goal. During that initial consultation, we talk for a full hour about their goals, their current routines and what they want to change. We come up with a plan we both feel good about, then as we’re about to conclude the session…

Client: “Oh yeah, and I’m registered for the Disney Half Marathon in 3 months!”

My inner dialogue: “NOOOOOO! This is going to ruin everything!”

Me on the outside: “Wow, that’s such a great goal!”

I know I can’t let them down right now. I know they are so pumped about the goals we set, as well as this big goal of running 13 (or even 26) miles. The idea makes sense on paper. Marathons are long, grueling, calorie-burning events. So wouldn’t training for one fast track you to dropping pounds?

Here’s the truth: marathon training and weight loss are usually competing goals. Trying to do both at the same time sets people up for frustration, not success.

Not because running is bad. It’s not. Running a half or full marathon is an incredible personal challenge BUT running long distances and losing weight require opposite strategies:

• Running long distances demands fuel. Your body relies heavily on quick-digesting carbs (think sports gels and drinks, chews, or even jelly beans) to perform.
• Weight loss requires a calorie deficit. That means eating less food overall, not constantly topping up on sugar mid-run.

Trying to do both at once is like pressing the gas and the brake at the same time.

Appetite, Hunger, and Carbs

Long-distance running revs up your appetite. After burning through your glycogen stores during a long (over 1 hour) run, your body needs sugar for quick fuel. That’s why marathoners have to eat mid-run. And what works best for refueling your run does not match what you would typically eat if you wanted to lose weight… snacks like gels, waffles, or candy. This can also make cravings afterward feel impossible to control.

And let’s be real: after a 15-mile training run, most people don’t want baby carrots and hummus. They want bagels, pizza, and comfort food.

This is why so many distance runners don’t lose weight, despite burning huge numbers of calories. They end up eating those calories right back, oftentimes more.

The Time Trade-Off

Another reason marathons don’t pair well with weight loss? Time.

Most of our clients are busy professionals, parents, or both. Training for a marathon eats up a lot of hours every week. Those are hours that could otherwise be spent on strength training, mobility, recovery, meal planning, or meal prep. From an overall wellness perspective, running isn’t the most efficient way to change your body composition or improve health.

That doesn’t mean running can’t be part of a healthy lifestyle. I personally run 3 times a week (usually only one mile, aiming for a fast pace). But if your primary goal is weight loss, devoting most of your workout time to pounding the pavement isn’t the best return on investment.

Why Running Worked in Your 20s

Many people look back and say, “Running worked for me when I was younger. I lost a ton of weight training for a race in college.”

Here’s why it doesn’t translate to midlife:

• Metabolic changes: Younger bodies burn more energy at rest.
• Dieting history: If you’ve dieted for decades, your body has adapted and “learned” how to conserve energy.
• Hormones: A 40-year-old male new to exercise may drop fat more easily than a 40-year-old woman approaching menopause.

Your body evolves over time. What worked at 22 rarely works the same way at 42.

Strength Training vs. Long-Distance Running

Here’s the big difference:

• Strength training builds muscle, which raises your metabolism long-term and reshapes your body. It burns calories during the workout and increases calorie burn afterward.
• Running burns calories in the moment but doesn’t build muscle or boost metabolism in the same way.

With weights, you can train for 30–45 minutes, build strength, and recover without needing Gatorade or gummy bears to get through it. Appetite spikes are usually smaller and easier to manage.

That’s why, for weight loss, lifting wins almost every time.

Real Client Stories

One client of mine was deep in the Disney Marathon scene. Running a full marathon was her life goal. She had already done a few halfs. She also wanted to lose 50 pounds. I told her she was going to have to choose.

She decided to put weight loss on hold. She was already deep into her training and had paid for her race entry fee. We focused on training smart, fueling properly, and staying injury-free. She finished the marathon, got her medal, and checked that life goal off her list.

Afterward, when we shifted focus back to weight loss, she was amazed at how much easier it was. Without the constant marathon hunger, her appetite felt normal again. She got a bunch of time back that she devoted to planning and prepping meals ahead. She focused more on strength training and added in some low intensity, stress-relieving movement as well.

Don’t Compare Yourself to Runners on Instagram

A quick reality check: many of the fit runners you see online are not in weight loss mode. They’re maintaining their fitness, not actively trying to drop pounds.

Think about athletes like Cam Hanes. He looks great running ultramarathons, but he’s not trying to lose 20 pounds. He’s already at his goal weight and cross-trains heavily. His goals are not your goals.

So What’s the Right Approach?

• If your main goal is the marathon: Fuel for performance. Eat the carbs, train hard, and focus on finishing strong. Save weight loss for later.
• If your main goal is weight loss: Prioritize strength training, moderate cardio, and consistency in your nutrition. Running can stay, but keep your runs at 10Ks or less.

The Bottom Line

Running a marathon is an amazing accomplishment, but it’s not a weight loss strategy. For most people, it makes weight loss harder.

If you love running, run! If you want to lose weight, focus on food intake, strength training, and stress reduction. If you want both, pick which goal is most important to you right now, go for it, and put the other on hold.

About the author: Megan Ware, RDN, LD, is a registered dietitian nutritionist in Orlando, FL. She owns the private practice, Nutrition Awareness, where she teaches other entrepreneurs how to maximize their productivity and performance with nutrition. She is the author of the book The Optimized Life: A Nutrition Guide for Entrepreneurs and co-host of the Nutrition Awareness Podcast.

If you need help losing weight, improving your performance, or increasing your energy, schedule your initial consultation here.