Half Marathon Training Plan for Weight Loss
Train for a half marathon and lose weight at the same time: aerobic volume that burns fat steadily while building your fitness to 13.1 miles.
The plan, week by week
Minutes per week. Tap a week.The half marathon rewards aerobic engine more than raw speed. The runners who struggle most are those who train like 5K runners, carrying too much intensity and not enough easy aerobic volume. Sustainable progression, quality long runs, and one threshold session per week is the formula that holds up across conditions. This plan is built for runners using running to support sustainable weight loss: the structure, pacing guidelines, and weekly progression are calibrated to your specific situation, not a generic template.
Fuelling half marathon long runs when you're losing weight
Long runs of 90 minutes or more are where weight-loss runners most often go wrong. Running long without enough fuel can feel virtuous, but it makes the run harder, slows recovery and often leads to a big wave of hunger later in the day. Before a long run, eat a proper breakfast with carbohydrate in it, and take something during the run once it goes past about 75 minutes. Treat long-run days as days when you eat more, not less. Your balance across the week matters far more than any one day. Over a half marathon block, steady fuelling also means you gain the fitness you are training for.
Why the scales can stall during half marathon training
Half marathon training can confuse anyone tracking their weight. As long runs and weekly volume build, your muscles store more carbohydrate, along with the water that comes with it, so the scales can rise slightly or stall for a few weeks even while your body is changing. That is normal. Tired muscles also hold extra water for a day or two after hard sessions and long runs. Weigh yourself at the same time of day, and look at the trend over a month rather than any single reading. During a build, how your clothes fit, your waist measurement and your pace at easy effort are better guides than the daily number.
How running and weight loss actually work together
Running creates a caloric demand that, with appropriate food intake, drives fat loss. The mistake most people make is under-eating relative to training load, which impairs recovery, reduces training quality, and paradoxically stalls weight loss as the body adapts to a perceived energy deficit. A moderate, sustainable caloric deficit of 250–400 kcal per day, combined with progressive training volume, is more effective than aggressive restriction.
Why easy aerobic running is the fat-loss sweet spot
At low intensities, fat is the primary fuel source. As pace increases toward threshold and beyond, the body shifts to burning glycogen. Counter-intuitively, running at a comfortable conversational pace — not pushing hard — maximises fat oxidation per session and allows you to recover for the next session. Building easy aerobic volume is the most sustainable fat-loss running strategy.
Fuelling training without undermining the goal
Training fasted (before eating) can feel productive for fat loss, but the evidence for it improving outcomes over fed training is weak, and it meaningfully increases injury risk and reduces quality on harder sessions. Eating a small amount before runs longer than 45–50 minutes, and recovering with protein within 30–45 minutes post-run, supports muscle retention and training quality — both of which protect long-term results.
Training philosophy
The half marathon rewards aerobic engine more than raw speed. The runners who struggle most are those who train like 5K runners, carrying too much intensity and not enough easy aerobic volume. Sustainable progression, quality long runs, and one threshold session per week is the formula that holds up across conditions.
Questions
How many days per week does this half marathon plan require?
Most sessions in this plan run four to five days per week, including one quality session, a long run, and easy aerobic running. The plan is designed to be adjustable — with Daash, Claude can restructure it around your available days each week.
Do I need a GPS watch to follow this half marathon training plan?
A GPS watch or running app is helpful for tracking pace and distance, but not strictly required. Effort-based running (using a scale of 1–10 perceived exertion) works well for easy runs. For quality sessions where specific paces matter, a watch becomes more valuable.
What should I eat before a long run?
For runs under 60–75 minutes, eating beforehand is optional. For longer runs, a light carbohydrate-based meal two to three hours before the session — oats, toast with banana, or a rice-based option — provides fuel without gastrointestinal issues. Avoid high-fat, high-fibre, or unfamiliar foods on long run mornings.
How does Daash adapt the plan if I miss a session?
Daash sees missed sessions in your Garmin data. Tell Claude why — illness, fatigue, life — and it reworks the coming week: redistributing sessions, reducing volume if needed, or adjusting the next quality session, then updates the workouts on your watch.
Do I need to take gels or nutrition during training for a half marathon?
For long runs over 75–80 minutes, practising race nutrition is valuable. Train with the gels, chews, or drinks available at your target race so your gut is adapted before race day. Do not try a new nutrition product for the first time on race morning.