My Garmin Said I Lost 4 Pounds of Water on a 90-Minute Run. Miami Heat Doesn't Care About Your Watch.
4.2 pounds. That's what my Garmin scale told me I lost after a 90-minute run last Tuesday. Not fat. Water. I stepped on the scale before and after, wearing the same clothes, and the difference was 4.2 pounds. That's two liters of fluid. Gone. In an hour and a half. In Miami. In June. At 6 AM, which was supposed to be the "cool" part of the day.
I've been running in Miami for eight years. I thought I knew heat. I thought I knew hydration. I was drinking 20 ounces of water before the run, carrying 16 ounces during, and refilling when I got home. That was my protocol. That was what the magazines said. That was what kept me alive through seven Miami summers.
But 2026 is different. The World Cup is coming. The heat season started in May instead of June. And Miami-Dade County's heat action plan is now active from May 1 through October 31 β the longest heat season on record. I checked the data. Since 1970, Miami has gone from 84 days above 90Β°F to 133 days. That's almost half the year. And my old hydration protocol was built for 84 days, not 133.
The run that cost me 4.2 pounds was not extreme. It was 8 miles at an easy pace. Heart rate zone 2. The kind of run I do three times a week. But the temperature was 82Β°F at 6 AM, with 78% humidity. The wet-bulb globe temperature β the real measure of heat stress β was 28Β°C. That's the threshold where FIFA mandates hydration breaks. I was running in World Cup conditions, alone, with a 16-ounce water bottle.
I called my friend Dr. Chen, who works sports medicine at the University of Miami. I told him the numbers. He was not surprised. "Jordan, you're a heavy salt sweater. In that humidity, you're losing 1,500mg of sodium per hour. Your 16-ounce bottle has zero sodium. You're basically diluting yourself."
Diluting myself. That phrase stuck with me. I was drinking water, losing salt, and creating a condition called hyponatremia β low blood sodium. The symptoms are subtle at first: fatigue, headache, nausea. Then they get worse. Confusion. Seizures. In extreme cases, death. And I was doing it three times a week because I thought water was enough.
Dr. Chen recommended a simple protocol. Pre-hydration: 16-20 ounces of electrolyte solution 2-3 hours before the run. During: 16-32 ounces per hour, with 300-700mg of sodium. Post-run: weigh yourself. For every pound lost, drink 16-20 ounces of fluid with electrolytes. Not plain water. Electrolytes.
I rebuilt my entire hydration strategy. I bought insulated bottles. I started mixing my own electrolyte solution β 1,000mg sodium, 200mg potassium, a pinch of magnesium. I set phone reminders every 45 minutes during outdoor activity. I shifted my long runs to before 7 AM or after 7 PM. And I started tracking urine color. Pale yellow = good. Dark amber = danger zone.
The results were immediate. My next 90-minute run, I lost 1.8 pounds instead of 4.2. My energy levels were stable. I wasn't crashing at mile 6. And I wasn't waking up at 3 AM with calf cramps β a symptom I had blamed on "getting older" but was actually dehydration.
Here's what I want you to understand. Miami heat is not a joke. It's not a minor inconvenience. It's a physiological stressor that can kill you if you don't respect it. The old advice β "drink 8 glasses a day" β was written for people in temperate climates. In Miami, in 2026, with 133 days above 90Β°F, that advice is dangerously inadequate.
If you're active in Miami β running, cycling, walking the dog, gardening, anything β you need electrolytes. Not just water. Not coconut water, which has 250mg of sodium per liter when you need 1,000. Not sports drinks, which are mostly sugar and marketing. You need sodium. You need potassium. You need a plan.
The World Cup is coming to Miami this summer. FIFA knows the heat is serious. They're mandating hydration breaks at minute 22 of each half. Three minutes. For professional athletes. If the best-conditioned humans on the planet need scheduled breaks, what does that tell you about your weekend 5K?
It tells you to take this seriously. To measure your sweat loss. To replace your electrolytes. To not be the person who ends up in the ER because they thought water was enough.
β Jordan, from a kitchen in Miami where the electrolyte bottles are always full
