Why you bloat in the heat, what is happening in the body, and what helps

By Anna Cave-Bigley

By the end of a hot afternoon I am a different shape. Rings tight, waistband cutting in, fingers like little sausages, and a heavy, held feeling through the middle as though everything has come to a stop. For years I blamed lunch. I went through the usual suspects, dairy, gluten, something that did not agree with me, and I never found the answer because there was not one to find.

It took a few summers to work out that it was not what I had eaten. It was the weather.

If that is you in July, swollen and slow and half convinced you have developed an intolerance overnight, stay with me. The cause is simpler than the one you have been chasing, and once you can see what your body is doing, the fixes are obvious.

What the heat is doing

When you get warm, your body has one job: lose that heat before your core temperature climbs. To do it, the blood vessels near the surface of your skin widen, a process called vasodilation, so warm blood travels close to the surface and releases heat. It works. But widening those vessels raises the pressure inside them and makes the walls a little leakier, and fluid seeps out of the blood and into the surrounding tissue. Gravity decides where it settles: hands, feet, ankles, lower legs. That is heat oedema, and it is the puffiness you feel by evening. Your sausage fingers are not a reaction to your food. They are your body cooling itself.

Then comes the part that lands on your stomach. In the heat you lose water through sweat faster than you register, and thirst always runs a step behind the deficit, so you are usually behind before you feel like drinking at all. When you are low on fluid, digestion tends to slow. Dehydration has been shown to slow gastric emptying, the rate at which your stomach passes food on, so things sit longer. Lower down, the colon's whole job is to reclaim water from what passes through it. Short on fluid, it pulls back more than usual, what is left turns harder and drier, and the whole transit slows. Food sits. You feel heavy.

So the puffiness in your hands and the heaviness in your gut are not two separate verdicts on your lunch. They are two responses to the same conditions: a body managing heat and holding on to water. Different mechanisms, one trigger, and the trigger is the weather.

The layer almost nobody connects

Here is the bit that explains why some hot days are so much worse than others.

If you are in the back half of your cycle, the luteal phase, the week or so before your period, you are already retaining water before the heat gets anywhere near you. The hormonal shifts of the luteal phase drive a transitory increase in fluid retention, your kidneys holding on to more salt and water in the run-up to your period. The exact mechanism is still argued over, but the effect is familiar to most of us. It is why so many feel puffy premenstrually, and why ankle swelling turns up specifically in the late luteal phase for some women.

Now put a heatwave on top. Your cycle and your thermoregulation are both ordering your body to retain fluid at the same time. A hot week before your period is not the worst bloat of your life because something is wrong with you. It is two ordinary systems stacking. That alone takes the fear out of it, and it points you at what to do.

What helps: water, salt and small things

This is the part I have lived, and the changes are unglamorous and effective.

Drink before you are thirsty. Thirst arrives late, so load up your water in the morning instead of playing catch-up at four o'clock when you already feel terrible. Plain water is not always enough on a sweaty day, because you lose salts as well as fluid. A pinch of good salt and a squeeze of citrus, or a clean electrolyte, helps you hold on to what you drink. Premenstrually, lean on potassium-rich foods too, they help balance the sodium your body is busy clinging to.

Eat your water. Cooling, water-heavy foods do double duty, hydration plus minerals: cucumber, watermelon, courgette, leafy greens, citrus, tomatoes. Build the hot-weather plate around them.

Go lighter, more often. A big, heavy meal lands badly when digestion is already slow. Smaller plates through the hottest part of the day sit far better than one enormous lunch.

Move the fluid. The pooling is gravity, so work against it. A gentle evening walk, or five minutes with your legs up the wall before bed, does more for swollen ankles than sitting still and hoping. And ease off the things that pull water out of you and stall you further, too much alcohol and very salty processed food on a hot day are a fast route to feeling worse.

What helps: cool down, slow down.

Two more things, and they cost nothing.

The first is the most obvious, and the one I forget every single year: cool the body itself. The puffiness is heat, so the quickest way to take the edge off is to bring your temperature down. A cool shower before bed, cold water on the inside of your wrists and the back of your neck, a swim if you can get to water, and staying out of the worst of the midday sun instead of pushing through it. Loose, natural fabrics over anything that clings. None of it is clever, and all of it works, because it goes at the cause rather than the symptom.

The second is for the gut directly, and it is the part I wish someone had shown me sooner. When digestion has stalled, you can coax it along by hand. Slow the meal down first: sit, chew properly, and try not to eat standing up or on the move, which makes you swallow air and bloat more. After dinner, rather than folding onto the sofa, take a slow ten-minute walk, or lie down and breathe low into your belly for a few minutes. Both keep things moving. And there is the old remedy of a gentle abdominal massage, a few slow circles in a clockwise direction, following the natural path of the gut. It sounds too simple to count, but it has been studied in a randomised trial, where it reduced the severity of digestive symptoms and abdominal pain. Five slow minutes before sleep, no equipment, nothing to buy.

What helps: the herbs

Hilary formulates everything we make, and she built The Digestive for days like these. I will let the plants speak for themselves.

Fennel is the one your grandmother already knew about, the seeds people chew after a heavy meal. That tradition rests on something real: fennel is a carminative, which is the old word for a plant that helps settle a gassy, cramping gut, and its main compound, anethole, relaxes the smooth muscle of the digestive tract. The modern research is catching up to the folklore. In one randomised, placebo-controlled trial of 121 people with IBS, a combination of fennel essential oil and curcumin improved symptoms and quality of life over thirty days. That was concentrated oil paired with another herb, not a cup of tea on its own, so I will not pretend a brew does the identical job. But it is why fennel has earned its long reputation, and in our blend it sits among the botanicals traditionally used to ease bloating and soothe a tight stomach.

Holy basil, or tulsi, and cardamom carry the warmth. Both are revered in Ayurvedic tradition for digestive comfort, and tulsi infusions have a long documented history of use for gastric complaints. Cinnamon and lemon verbena bring their own settling, carminative traditions. Nettle, rich in minerals, has long been valued in herbal tradition for supporting the body's water balance. Oat straw and moringa are nutritives, in for the minerals they carry rather than any digestive trick. Together it is a blend traditionally used to support digestion and ease bloating.

In summer I take it cold. Brew it strong, pour it over ice, keep a jug in the fridge. A cold, lightly spiced infusion you want to reach for in the heat does the herbs and the hydration in one glass.

The honest line

Most summer puffiness is harmless and lifts once you cool down, rehydrate and get the fluid moving. That is the ordinary version, and it is the one this whole piece is about.

Some swelling is not the heat, and the difference is worth knowing. Swelling that comes on suddenly, sits on one side only, or is painful, red or hot to the touch is a same-day call to your doctor, not something to wait out. And if you are pregnant, swelling deserves more caution still, particularly if it comes on quickly, affects your face or hands, or arrives with a headache or changes in your vision, because it can be an early sign of pre-eclampsia. Do not sit on that one. Get seen.

So next time you are puffy and slow by sundown, check the thermometer before you indict your lunch. Then drink the glass of water you do not yet feel like drinking.

Anna x

The science, sourced

• Heat oedema and the vasodilation behind it: StatPearls (NCBI Bookshelf), Heat Illness

• Dehydration and digestion: van Nieuwenhoven et al., Effect of dehydration on gastrointestinal function at rest and during exercise in humans

• Cyclical fluid retention: MSD Manual, Premenstrual Syndrome and Hormonal and Volume Dysregulation in Women With Premenstrual Syndrome, Hypertension (AHA)

• Fennel and digestive symptoms: Portincasa et al., Curcumin and Fennel Essential Oil Improve Symptoms and Quality of Life in Patients with Irritable Bowel Syndrome

• Holy basil, traditional use: Cohen, Tulsi, Ocimum sanctum: A herb for all reasons

• Abdominal massage and digestive symptoms: Lämås et al., Effects of abdominal massage in management of constipation, a randomized controlled trial

DISCLAIMER

The SABI blog and articles are not meant to instruct or advise on medical or health conditions, but to inform. The information and opinions presented here do not substitute professional medical advice or consultations with healthcare professionals for your unique situation.

ABOUT ANNA

Anna is a Co-founder and the CEO of The SABI and has spent the past 13 years working in or for governments, senior businessmen and politicians around the world. Living in Bogota, Colombia, she recently renovated one of Colombia's oldest and most iconic coffee estates, developing a unique taste and travel experience. She lives with her husband and three boys Lorenzo, Alfie and Salvador who are responsible for the beautiful journey that inspired her to pursue The Sabi.

HORMONAL & PROUD

The SABI was created to help women through the hardest moments of pregnancy, childbirth, postpartum and every stage that follows. We want to change the story around our hormones, from one of taboo, embarrassment and loneliness to one of awareness, and even pride.

More than a wellness brand, The SABI is a line of rituals, supportive tools and functional herbal remedies, tested by hundreds of years of traditional medicine and now backed by modern science. It was conceived by women who have lived the joys and the deeper costs of bringing a child into the world, of a heavy or difficult period, of miscarriage and trouble conceiving.

Consider this an invitation to know your body and its cycles, to learn to work with them at any stage of life, and to know that support exists. Look for the right sources, know there is help, and know that you are not on your own.