If you’re feeling more lethargic, achy, or generally “off” during a heatwave, it’s not just in your head. There are three specific things that happen inside your body when temperatures rise that lead to increased inflammation, and inflammation is the root cause of most disease processes, including aging itself. Here’s what those three factors are, and what actually helps with each one. (Based on insights from Dr. Sunil Dahand)
Key takeaways
- Hot weather increases inflammation through three main pathways: dehydration, decreased mobility, and oxidative stress.
- Fluid needs can rise to 10-15 cups of water per day in very hot weather, along with adequate electrolytes.
- Reduced mobility in the heat can cause muscles to suddenly atrophy, which is directly linked to inflammation.
- Antioxidant-rich foods such as blueberries, broccoli, and bell peppers help counter oxidative stress that increases in heat.
- People with high blood pressure, kidney disease, or heart failure should control salt intake with specific guidance from a doctor.
Reason No. 1: Dehydration
Even on a typical day, most people don’t drink enough fluids, and adequate hydration is essential for basic cellular function — and the kidneys especially depend on it. In hot weather, fluid loss through sweat greatly exacerbates this problem. A reasonable baseline is to drink several cups of water a day, but on very hot days the number can rise to 10 or even 15 cups depending on how much you sweat.
Electrolytes are important here too – potassium, magnesium and salt. Since heavy sweating also means salt loss, aggressively reducing sodium during hot weather doesn’t necessarily benefit you. However, if you have high blood pressure, kidney disease, or heart failure, salt intake is something that should be controlled specifically with your doctor rather than a general rule.
As for what to drink: plain water remains the best option. If large amounts of water seem unappealing, a slice of lemon can help make it more palatable. Tea and coffee have a mild diuretic effect but contribute positively to overall hydration – water is still the best option, but they don’t work against you either.
Reason No. 2: Decreased mobility
When it’s hot, especially without reliable air conditioning, people naturally move less — sitting or lying down feels much more inviting than getting up and walking. But decreased mobility can lead to muscle atrophy surprisingly quickly, and this has a direct link to inflammation. Going outside early, before the heat reaches peak, doing light movements indoors with fans on, or doing simple activities like using dumbbells all help prevent it from getting worse.
Cause #3: Oxidative stress
Oxidative stress refers to the buildup of free radicals as a byproduct of ongoing chemical processes in the body, and research shows that this process increases in hot weather. Hydration and movement all help to combat this, but eating antioxidants is also important – especially from colorful fruits and vegetables rich in vitamins A, C and E.
Blueberries especially stand out; One serving can contain more antioxidants than five servings of many other fruits or vegetables combined. Broccoli and red, yellow, or green peppers are also strong choices. If you are diabetic or have low blood sugar, be mindful of your fruit servings and prefer whole fruit to juice, because juice lacks the fiber that helps offset the effect of sugar.
Put it all together
When temperatures rise, you’re more likely to become dehydrated, move less, and experience more oxidative stress — all three of which directly lead to inflammation. Staying on top of your water and electrolyte intake, keeping some form of movement into your day even when it’s uncomfortable, and leaning into antioxidant-rich foods like blueberries and colorful vegetables can help offset these effects.
source: Dr. Sunil Dhand
Frequently asked questions
How much water should I actually drink in hot weather?
A reasonable baseline is several cups a day, but in very hot weather it can go up to 10 or even 15 cups depending on how much you sweat. Individual needs vary, especially with certain medical conditions.
Should I reduce salt when it’s hot?
Not necessarily, heavy sweating also causes salt loss, so excessive sodium restriction in hot weather is not automatically beneficial. However, anyone with high blood pressure, kidney disease, or heart failure should follow their doctor’s specific instructions rather than general advice.
Why do I feel less like exercising when it’s hot?
It’s a natural response: heat makes movement feel less attractive, and many people resort to sitting or lying down. The problem is that decreased mobility can lead to muscle atrophy fairly quickly, which is directly related to inflammation, so finding ways to stay active is still important.
What foods help fight the effects of heat on the body?
Colorful fruits and vegetables rich in vitamins A, C and E are particularly beneficial, with blueberries standing out as a particularly concentrated source of antioxidants, along with broccoli and bell peppers.
Quick start checklist
- ☐ Drink water throughout the day, especially on hot days
- ☐ Add electrolytes — potassium, magnesium, and salt — especially if sweating is heavy
- ☐ Start moving early, before the heat peaks, or indoors with the fans running
- ☐ Add blueberries, broccoli, and colored peppers to your meals
- ☐ Whole fruit is preferred over juice if controlling blood sugar
- ☐ Consult your doctor about salt/fluid intake if you have high blood pressure, kidney disease, or heart failure
Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. If you have a condition that affects your fluid, electrolyte or sodium intake — such as high blood pressure, kidney disease or heart failure — consult your doctor for advice specific to your condition.
