Most people employ diets to lose weight and get in shape. But what if your meals, and the times at which you eat them, could keep your brain healthy too? New research suggests eating all of your day’s meals and snacks within a nine-hour window, and eating your last meal four or more hours before bed, could slow down cognitive decline and reduce your risk of dementia. You may recognise this as a form of intermittent fasting – a general protocol made famous by Michael Mosley and his 5:2 diet. But does this mean we should all be intermittent fasting for optimal health?Sadly, as with anything in the health and fitness space, the answer is not so clear cut. What the study saysThe trial enrolled 47 overweight or obese women aged between the ages of 50 and 79. They were all guided to reduce their calorie intake by 500 per day. Of the 47, 26 women consumed their daily calories within a window of nine hours or less, while the remainder ate over a typical 12-hour period. On average, the women lost 6.8kg after six months. But those with the nine-hour eating window enjoyed bonus benefits for their brain. “There was a modest effect of time-restricted eating to improve spatial planning and problem-solving, and on reducing errors related to memory and learning,” says Sue Shapses, professor of Rutgers University and the study’s lead investigator.“These outcomes suggest a better ability to remember information during everyday tasks, and reduced mistakes related to memory, attention and problem-solving. Reductions in the eating window predicted greater improvements.”However, researchers add, the trial was relatively small and further studies are needed to confirm the findings. They also hope to identify why these benefits occur, and how time-restricted eating interacts with circadian rhythm, nutrient-sensing pathways, inflammation and metabolic health.Read more: Longevity expert says this diet is more effective than Ozempic at changing the human bodyA nine-hour eating window has been linked to several benefits for your brain, but fasting expert Dr Valter Longo has warned against it being any longer than that (Getty/iStock)Should I be intermittent fasting?The study above is interesting, suggesting a nine-hour eating window could deliver improvements in cognitive performance alongside weight loss in overweight people. But 2026 research published in the Cochrane Library found that “compared to regular dietary advice, intermittent fasting may result in little to no difference in weight loss or quality of life”.Any reduction in calories can lead to weight loss. This is no different to any other dietVassiliki Sinopoulou, registered dietitian and lecturerIf you consume less energy than you burn, you will lose weight – this is the first law of thermodynamics in action. If you have less time to eat in your day, you tend to eat less, tipping this equation in favour of those looking to shed pounds. This is why intermittent fasting works for weight loss. But the common denominator – creating an energy deficit – is why pretty much every other type of diet does too. As registered dietitian and University of Lancashire lecturer Vassiliki Sinopoulou puts it: “Any reduction in calories can lead to weight loss. This is no different to any other diet.”The most important aspect of any diet is adherence – can you follow it sustainably for a prolonged period of time? If so, it will invariably have the desired effect. If the structure and clear guidelines of intermittent fasting fit your routine and mindset, it could be a good option for helping you manage your weight. If it doesn’t, eating an appropriate number of calories for your activity levels in any way, shape or form will still do the job. Read more: So, if intermittent fasting doesn’t work for weight loss then what does?Intermittent fasting could work for some people – but not everyone (Getty/iStock)The bonus benefits of intermittent fasting Fasting may not be provably superior to any other form of diet for weight loss. But some say it offers bonus perks that are worth pursuing. “There is research to suggest fasting can lead to improvements in cholesterol levels, improvements in blood pressure and lower inflammation in general, which is a risk factor for cardiovascular disease,” says Heart Research UK nutritionist Amie Leckie.“Digestion also takes a lot of energy. Many people eat all day long without realising, and I think a lot of that comes down to people not balancing their meals properly – they’re not eating enough protein or fibre, so they feel hungry an hour after a meal.“When we do intermittent fasting, we give the body a break. We give it time to work on things at a cellular level and repair, so we do see certain benefits from that such as reducing CRP (C-reactive protein) levels, which are a marker of inflammation, and cognitive benefits as well.”Many people eat all day long without realising, and I think a lot of that comes down to people not balancing their meals properlAmie Leckie, nutritionist at Heart Research UKDr Valter Longo, the longevity pioneer who inspired many of Dr Mosley’s fasting-related endeavours, is leading research into its extended benefits. When I spoke to him last year, he was understandably supportive of some forms of fasting. But he also stressed the need for nuance – and opposed 16-hour fasting windows, similar to those seen in the study above. “People shouldn’t think that anything you do [with regards to adopting a diet] is right, because a lot of people are doing things they think are good for them that are actually associated with a shorter life; a ketogenic diet, a low-carbohydrate diet, 16 hours of fasting, skipping breakfast, there is a long list of things,” he said. “There is 30 years of data indicating that you are going to live a shorter life and you will have more [risk of] cardiovascular disease [if you skip breakfast].”One potential mechanism for this is the impact of 16-hour fasts on cholesterol levels, Dr Longo says. “You may view [16-hour fasts] as an anti-statin – it’s increasing your cholesterol rather than lowering it,” he said.“We know that statins lower your risk of cardiovascular diseases, heart attacks and cardiovascular events. It makes sense that if you did the opposite, that should increase your cardiovascular disease and events. And of course, we know that bad cholesterol levels correlate with cardiovascular disease.”Read more: Three mistakes nutritionists want you to stop making with your mealsA Mediterranean diet contains many of the hallmarks of healthy eating (Getty/iStock)How should you eat for better health?With the internet at your disposal, you can easily find data, articles and information to support almost any dietary approach. Therein lies the confusion. Some people will report life-changing results from intermittent fasting; some will experience little change. The same can be said for research in many cases – some studies are for intermittent fasting, others are against it. This applies to almost any type of diet. A 2020 review sought to put the “best diet” argument to bed, comparing research around several popular strategies including low-fat, low-carbohydrate, ketogenic, high-protein, Mediterranean, paleo, low GI, Nordic, vegetarian and intermittent fasting. It concluded: “There is no single best strategy for weight management. Reducing daily calorie intake is the most important factor for weight loss. “...Except for energy deficit, there seems to be no significant difference between macronutrient composition-based diets. Improvement in cardiometabolic factors strongly depends on the degree of weight loss. “However, as in the Mediterranean diet, increasing consumption of fruits and vegetables and intake of healthy fats (including monounsaturated as well as polyunsaturated fats) can be a healthy strategy for weight loss and maintenance.”This aligns fairly well with Dr Longo’s “longevity diet”, which follows a 12-hour eating window in line with your body’s circadian rhythm – or in-built body clock which follows natural night-day cycles. “It almost completely eliminates red meat, it keeps white meat very low, and fish is eaten maybe three or four times a week,” he says.“There are lots of vegetables, lots of legumes, lots of tree nuts, wholegrain cereal and some fruits. These are some of the ingredients that, consistently all over the world, have been associated with living a longer, healthier life.”The study’s results also agree with the insights of the nutrition experts I interview weekly. It seems that, when in doubt on how best to eat, we can fall back on tried and trusted advice that has outlasted innumerable trends, fads and crash diets. Focus on whole foods, eat your greens, swerve late-night snacking – pretty much everything your parents told you to do as a child. Perhaps “mother knows best” is more than just a phrase, after all. Read more: Experts know that UPFs are poisoning us – here is what to remove from your diet now