Want to really shift the pounds in January? Get drinking water

Too often, we mistake thirst for hunger (and vice-versa).

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If you’ve been struggling to come up with a suitable New Year resolution, may I suggest a determined plan to drink more? That might sound superficially attractive (depending on what kind of New Year you had) but I should make clear from the outset that it’s water, not alcohol, that I have in mind.

Ensuring adequate hydration has certain benefits, medically speaking. A good fluid throughput reduces the chance of urinary tract infection, and helps prevent attacks of gout and kidney stone formation in people prone to these conditions. If we’re short of water, the bowel will reabsorb every last drop from what doctors euphemistically term the “stool”, which can lead to constipation. And our kidneys function best when there is plenty of water around – they respond to dehydration by concentrating urine to conserve body water, but in doing so they can sustain damage through metabolic stress.

Aside from these medical aspects, there may be softer benefits. As the body starts to dehydrate, water within cells is drawn out into the circulation. The resultant cellular water loss can affect function in a variety of tissues. Athletes’ fluid balance has been the subject of extensive research, and even mild levels of dehydration measurably reduce physical performance. Studies of brain function have shown conflicting results, but overall it appears that mild to moderate dehydration impairs concentration and the ability to think through complex tasks. Headache is a common symptom of water depletion and, although it’s not a miracle cure, studies show that the severity and duration of headaches can be reduced by optimising hydration. So frequent swigs from a bottle of water may help ensure we’re in top condition to tackle our day.

Beyond this, water is a critical ally in the fight against the modern plague of obesity. Quenching our thirst with pretty much any other drink freights in energy along with the H2O, adding to our overall calorie load. There is also some suggestion that we readily confuse thirst for hunger. This might sound daft, but both sensations are mediated by the same region of the brain, and our highly adaptable brains rapidly forge associations between behaviours and the biological drives that they satisfy. All foodstuffs contain water, so it has always been possible to ease thirst by eating; but many of the fluids we consume nowadays are highly calorific, so we often sate our hunger by drinking. As a consequence of these crossed wires, we may be taking substantial excess energy into our bodies when all we’re after is some H2O. Anyone wanting to tackle an expanding waistline should respond to apparent hunger pangs with a good drink of water. If twenty minutes later you no longer crave food, then what you were experiencing was thirst.

As we age, our sense of thirst diminishes, and many elderly people completely lose the cues that ordinarily prompt fluid intake. Of itself, this increases susceptibility to urinary tract infection, but dehydration is also a frequent and severe complication of otherwise minor illnesses such as flu or gastroenteritis in this age group. The rapid downward spiral of low blood pressure, kidney failure and mental confusion frequently leads to hospital admission, or even death. We assume that if someone isn’t thirsty then they’re not short of fluids, but the most important advice I give elderly patients is to ensure that they drink regularly, even if they don’t feel like it.

If you are interested in increasing your own daily water intake, get yourself a bottle to refill from the tap, rather than adding to the mountain of plastic waste we produce. How much to drink varies according to individual circumstances, but two litres over 24 hours should be fine – three at a push. The best gauge is your urine colour: pale straw is what you’re looking for. Darker suggests you should drink more, but if you’re constantly peeing stuff that’s as clear as Evian then you’re overdoing it. And with that, I wish you a happy, hydrated new year.

This article appears in the 05 January 2016 issue of the New Statesman, Divided Britain