After 6 months of keto, I learned that hydration isn’t just about drinking water – it’s about completely rethinking your relationship with fluids, electrolytes, and your body’s new way of functioning. What started as a simple diet became a masterclass in understanding how dramatically ketosis changes your hydration needs, and frankly, I wish someone had warned me properly about what I was getting into.
When I first started keto back in January (perfect timing for a New Year’s resolution, wasn’t it?), I thought I had it all figured out. I’d read the basics online, stocked up on avocados and eggs from Tesco, and assumed that drinking my usual eight glasses of water would keep me sorted. How wrong I was! Within days, I felt like I’d been hit by a bus, and it took me weeks to realise that my hydration game was completely off.
Today, I want to share everything I’ve learned about staying properly hydrated on keto – from the mistakes that left me feeling dreadful to the daily routine that finally got me thriving. Because let’s be honest, the internet is full of generic advice that doesn’t consider what it’s actually like doing keto in Britain, with our unpredictable weather, pub culture, and tendency to survive on tea and good intentions.
Why keto threw my hydration completely off balance
In my first week of keto, I couldn’t understand why I felt absolutely terrible despite doing everything “right” according to the articles I’d read. I was eating the right foods, avoiding carbs religiously, and drinking what I thought was plenty of water. Yet there I was, feeling like I had the world’s worst hangover without having touched a drop of alcohol (more’s the pity).
What I didn’t realise at the time was that keto essentially flushes your system clean in the first few weeks. Your body dumps all its stored glycogen, and with it goes a massive amount of water – we’re talking several pounds worth. It’s like someone pulled the plug on your internal reservoir, and suddenly you’re running on empty without realising it.
The science bit (bear with me, it’s important): normally, your body stores carbohydrates as glycogen in your muscles and liver, and each gram of glycogen holds onto about 3-4 grams of water. When you go keto and stop eating carbs, your body burns through these glycogen stores in a matter of days, releasing all that water. It’s brilliant for quick weight loss (hello, instant gratification!), but absolute murder for staying hydrated.
Mind you, this isn’t just about feeling a bit thirsty. This water loss throws your entire electrolyte balance out of whack. Sodium, potassium, magnesium – all the minerals that keep your body functioning properly – get flushed out along with the water. And here’s where it gets particularly British: our typical response to feeling rough is to have a cup of tea and soldier on, which actually makes the dehydration worse because caffeine is a diuretic.
The symptoms that caught me completely off guard
These warning signs showed up within days, though I was too stubborn to connect them to my new diet initially. The headaches were the first thing I noticed – not your average tension headache, but a proper skull-crushing affair that paracetamol barely touched. I blamed it on work stress (classic mistake) and carried on.
Then came the fatigue that felt like someone had drained my batteries overnight. I’m normally quite energetic, but by day three of keto, I was struggling to concentrate during my morning commute on the Tube. I actually fell asleep standing up on the Northern Line – not my finest moment, and definitely not normal for someone who usually reads the entire Metro journey.
The brain fog was perhaps the most frustrating symptom. I’d sit in meetings at work and feel like my head was stuffed with cotton wool. Simple decisions became monumentally difficult, and I couldn’t hold a conversation without losing my train of thought halfway through. My colleagues definitely noticed, though they were too polite to say anything (bless them).
But the muscle cramps were what finally made me pay attention. I woke up one night with the most excruciating calf cramp – the kind that has you hopping around the bedroom swearing like a sailor. When it happened three nights running, I finally admitted that something was seriously wrong with my approach.
Looking back, I should have connected these dots much sooner. But when you’re in the thick of it, suffering from brain fog and fatigue, logical thinking isn’t exactly your strong suit. It’s rather like trying to solve a puzzle while someone’s shining a torch in your eyes.
What my GP didn’t tell me about keto and water
When I spoke to my doctor about keto (partly out of due diligence, partly because I was feeling so dreadful), the advice I got was… well, let’s just say it wasn’t particularly helpful for keto-specific hydration needs. The standard NHS guidance is solid for general health, but it doesn’t really address what happens when you completely change how your body processes energy.
My GP’s main concern was whether keto was safe long-term (fair enough), and his hydration advice was the standard “aim for 6-8 glasses of water daily.” Which is fine for normal circumstances, but when you’re in the early stages of keto and your kidneys are working overtime to flush out ketones and excess water, that’s simply not enough.
To be fair to the medical profession, keto wasn’t nearly as mainstream when I started as it is now. Most GPs were (and probably still are) more familiar with traditional low-fat diets than ketogenic approaches. So I found myself having to become my own advocate, researching reputable sources and learning to distinguish between solid science and internet nonsense.
The turning point came when I found some proper research papers about ketogenic diets and hydration. Buried in the academic jargon was gold: people on keto need significantly more water than the general population, often 3-4 litres daily rather than the standard 2 litres. More importantly, they need to actively replace electrolytes, not just hope they’ll get enough from food.
My daily hydration routine that actually works
My day starts with 500ml of water before my morning cuppa – and this was honestly the hardest habit to establish. I’m not naturally a morning person, and the last thing I wanted was to chug water when all I craved was tea. But it makes an enormous difference to how I feel throughout the day.
I keep a 1-litre bottle on my desk at work and aim to finish it by lunchtime. The trick is adding a pinch of sea salt and a squeeze of lemon – it makes the water more palatable and helps with electrolyte replacement. My colleagues thought I was mad at first (they’re probably not wrong), but several have copied the habit after seeing how much better I function.
Lunch break means another 500ml, usually with my meal. I’ve learned that drinking with food actually helps with digestion on keto, contrary to some advice you’ll read online. The afternoon sees me working through another bottle, especially if I’m feeling that 3pm energy dip that used to send me straight to the vending machine.
Evening hydration is where I had to get creative. Too much water before bed means midnight bathroom trips (not ideal when you live in a Victorian terrace with creaky floorboards), so I front-load my intake earlier in the day. However, I do have a small glass of water with electrolyte powder about an hour before bed – it helps prevent those dreadful middle-of-the-night cramps.
Weekends are different because my routine changes completely. Saturday morning fry-ups (keto-style, obviously) need extra water because of the higher sodium content. And if I’m having a few drinks down the pub (more on that later), I alternate alcoholic drinks with sparkling water. My friends have stopped taking the mickey out of me for it because I’m the only one who doesn’t feel dreadful the next morning.
Electrolytes: The missing piece I ignored for months
It wasn’t until month 3 that I realised water alone wasn’t cutting it. I was drinking loads, feeling reasonably hydrated, but still getting occasional headaches and energy crashes that didn’t make sense. A chance conversation with someone at my gym (who’d been doing keto for years) opened my eyes to the electrolyte piece of the puzzle.
The revelation was that on keto, your kidneys excrete sodium much more readily. In normal circumstances, your body holds onto sodium quite tightly, but in ketosis, you’re constantly losing it. And where sodium goes, water follows, which explains why I could drink litres and still feel dehydrated.
My first attempt at electrolyte replacement was those fancy sports drinks from the supermarket. Terrible idea – they’re packed with sugar and artificial nonsense that completely defeats the point of keto. I felt like an idiot when I read the label properly and realised I’d basically been drinking liquid Haribo.
The breakthrough came with proper electrolyte supplements designed for low-carb diets. I started with a powder from Holland & Barrett (not the cheapest option, but readily available), mixing it into my morning water. The difference was immediate and dramatic – no more afternoon energy crashes, far fewer headaches, and that general feeling of being slightly off just disappeared.
These days, I’m more strategic about it. I make my own electrolyte mix using sea salt, potassium chloride (available from most pharmacies), and magnesium powder. It costs a fraction of commercial products and I can adjust the ratios based on how I’m feeling. On hot days or after exercise, I increase the sodium. If I’m feeling a bit tense or struggling to sleep, I up the magnesium.
Hydration challenges in different situations
During last summer’s heatwave (remember that brutal week in July when the Tube was like a sauna?), I learned just how quickly keto hydration can go wrong in extreme conditions. Normal people struggle with heat, but on keto, dehydration happens frighteningly fast. I made the mistake of spending a day at a beer garden in Greenwich without adjusting my water intake, and by evening I felt absolutely dreadful.
Social drinking presented its own challenges, and this is where being British makes keto particularly tricky. Our entire social culture revolves around pubs, and “just having a soft drink” marks you as either pregnant, driving, or deeply antisocial. I’ve learned to nurse a gin and slimline tonic while secretly matching every alcoholic drink with a glass of water. The trick is ordering the water when you order your drink – bartenders are usually happy to oblige, and friends don’t notice as much.
Travel is another hydration minefield. Airport security means you can’t bring proper water bottles through, and buying water airside costs a fortune. I now travel with electrolyte tablets that I can drop into whatever overpriced water I buy after security. Train travel is easier – I pack a large bottle and refill it at stations when possible.
Work stress affects my hydration more on keto than it ever did before. When I’m under pressure, I forget to drink regularly, and the consequences are immediate and unforgiving. I’ve learned to set phone reminders every two hours – it sounds obsessive, but it prevents the afternoon crashes that used to derail my productivity.
Exercise hydration required complete relearning. Pre-keto, I could get away with having a drink after my workout. Now, I need to start hydrating an hour before exercise, sip throughout, and continue well after I finish. My gym bag now contains more electrolyte supplements than actual gym gear, but it’s the difference between feeling energised after exercise and feeling like death warmed up.
Resources that saved my keto hydration game
The game-changer for my hydration was finding reliable, science-based information that actually applied to doing keto in the UK. Too much online advice is American-focused and doesn’t consider our climate, lifestyle, or available products.
When I was struggling to get my hydration right on keto, I stumbled across beketo.uk which became my go-to resource for reliable, UK-focused keto advice. Their hydration guidance is spot-on and considers our British lifestyle – from dealing with unpredictable weather to managing social drinks down the pub. I still check their latest articles whenever I need to troubleshoot my keto routine.
For tracking my daily intake, I use a simple app called WaterMinder. Nothing fancy, but it sends gentle reminders and helps me visualise whether I’m on track. The visual element is surprisingly motivating – there’s something satisfying about watching your daily water bottle fill up on screen.
My kitchen scale became essential for mixing electrolyte solutions. Precision matters when you’re dealing with minerals that can taste awful if you get the ratios wrong. I invested in a decent digital scale from John Lewis that measures to the gram – it’s been worth every penny.
For electrolyte ingredients, I’ve found the best value comes from online suppliers rather than high street shops. Bulk Powders does excellent potassium chloride and magnesium supplements at reasonable prices. For sea salt, I just use Maldon – it’s more expensive than table salt, but the mineral content is superior and it dissolves beautifully.
The keto community on Reddit (r/ketouk specifically) has been invaluable for UK-specific advice. Where else would you learn that Tesco’s own-brand sparkling water is perfect for mixing electrolytes, or that boots stocks magnesium oil that’s brilliant for topical application when you’re feeling crampy?
What I wish I’d known from day one
Looking back after six months, the hydration learning curve was probably the steepest part of my entire keto journey. The food side came naturally enough, but getting hydration right took serious trial and error – mostly error, if I’m being honest.
The most important lesson: don’t wait until you feel thirsty to drink water. On keto, thirst is a late warning sign, and by the time you feel it, you’re already behind. I now drink water proactively throughout the day, whether I fancy it or not. It’s become as automatic as brushing my teeth.
Second crucial point: electrolytes aren’t optional extras, they’re essential. I wasted months feeling subpar because I thought water alone would suffice. Once I started properly replacing sodium, potassium, and magnesium, everything else about keto became easier – better energy, clearer thinking, improved sleep, fewer cravings.
The social aspect was harder to navigate than I expected. British culture makes it challenging to maintain proper hydration habits when you’re out and about. I’ve had to become quite assertive about ordering water alongside drinks, carrying my own bottles, and not feeling embarrassed about my hydration needs. Most people are actually quite understanding once you explain that it’s for health reasons.
Seasonality matters more than I anticipated. Winter hydration needs are different from summer, and I’ve learned to adjust accordingly. Central heating is incredibly dehydrating, so I actually drink more water during cold months than you might expect. Conversely, summer requires more active electrolyte replacement because of increased sweating.
If you’re just starting keto, my advice is this: prioritise hydration from day one. Don’t make my mistake of treating it as an afterthought. Get your electrolyte strategy sorted before you start, stock up on sea salt and magnesium, and prepare to drink more water than you ever have in your life. Your future self will thank you when you avoid the worst of the keto flu and actually enjoy the process rather than suffering through it.
Most importantly, be patient with yourself as you figure out what works. Everyone’s hydration needs are slightly different, and what works for someone else might need tweaking for your lifestyle, activity level, and preferences. The key is paying attention to how you feel and adjusting accordingly. After six months, proper hydration on keto has become second nature, but it definitely didn’t start that way!
