Drinking coffee first thing can dehydrate you, according to an NHS GP who warns that the morning brew may be setting people up for headaches and energy slumps before the day has properly begun.
Dr David Weinstein, a GP based in Brighton with more than 17 years of experience, has identified five common morning habits he believes are damaging health. While caffeine is not the enemy, he says the timing of that first cup matters far more than most realise.
The problem with coffee before water
“I’d love to see people start the day with a pint of water,” says Dr Weinstein, 49, who also works at One Day Tests. After an overnight fast the body is already dehydrated, and coffee’s diuretic effect can compound that deficit. He explains that headaches are a frequent consequence. “Less people would come to see me with headaches. It’s a simple, but very positive thing you can do.”
Dr Weinstein clarifies that coffee is fine to drink later in the day, but should not be relied upon as a source of energy. If you cannot get through the day without caffeine, he says, the real issue may be insufficient sleep – or an underlying health problem that warrants a GP visit. His own interest in energy and wellbeing was sparked by personal experience with low energy, which led him to complete a course at Harvard Medical School and establish the Sussex Wellman Clinic, specialising in men’s health and low testosterone treatment.
Sugary cereals: ‘criminal’ health claims
Many breakfast cereals marketed as healthy are little more than sugar hits, Dr Weinstein argues. He would like to see them “heavily taxed” and carry “cigarette packet-style warnings” about their sugar content. The NHS recommends adults consume no more than 30g of free sugars per day – roughly seven sugar cubes – yet a single serving of many cereals contains three cubes or more.
“With cereals, when something is considered to be part of a normal morning routine, and makes health claims like being ‘high fibre’, I think it’s criminal,” he says. His preferred alternative is Greek yoghurt with berries and nuts: “It’s still just chucking stuff in a bowl. It’ll take the same amount of time to put together as cereal and milk.”
Skipping breakfast fuels bad decisions
Rushing out without any breakfast can leave people ravenous by mid-morning, Dr Weinstein warns. “When you’re hungry you make unwise decisions.” Breakfast replenishes glucose, boosting energy and providing essential nutrients. Skipping it often leads to grabbing an unhealthy snack out of convenience. “Fasting for the morning only works if you’ve got a well-planned healthy lunch or breakfast, rather than rushing to the bakery for, maybe, a big sweet pastry.”
Morning doomscrolling delivers a cortisol hit
Even Dr Weinstein admits to the habit of reaching for his phone first thing. “It’s terrible – starting the day with stress and anxiety, checking emails and scrolling social media and the news. That instant hit of anxiety, instant bad news – it hits you straight away and it’s not how we’re designed to start the day.”
Research indicates that doomscrolling can worsen pre-existing depression and anxiety, leading to increased stress, fatigue and reduced productivity. Dr Weinstein recommends buying an old-fashioned alarm clock so the phone can be left outside the bedroom overnight, and avoiding touching it for the first 15 minutes after waking. Instead, he suggests light stretches and thinking of a few things to be grateful for. “We need a gentle introduction, otherwise it’s a cortisol hit much too early.”
Bed-to-chair culture and the case for morning movement
The fifth habit Dr Weinstein wants people to break is going straight from bed to chair – particularly common for those working from home. “Bed to chair is a toxic thing that has become normal,” he says. The UK population now sits for an average of 9.5 hours a day, a sedentary lifestyle linked to increased risk of obesity, diabetes, cardiovascular disease and premature death. A 2025 study by BMC Public Health confirmed that sedentary behaviour and lack of physical activity are associated with negative health outcomes influenced by one’s working environment and reduced daily steps.
Dr Weinstein says the solution is straightforward: aim for 15 minutes of gentle movement each morning, such as stretches or a short walk, ideally outdoors. For those commuting or working from home, a walk during a lunch break can also help. “Doing 15 minutes of movement clears your head, helps your mood and energy, and prepares you for the day.”
Studies suggest that morning exercise, particularly between 8am and 11am, may offer the most significant benefits in reducing the risk of cardiovascular disease and stroke. It boosts metabolism, improves mental clarity, reduces stress and enhances sleep quality – a direct counter to the sedentary rut that has become normal for so many.