Your prescription for 2011 is…

… be slightly overweight, don't exercise too much and stop peeling your fruit and veg. Follow these seven simple steps to better health.

· Dr Tom Smith

· The Guardian, Saturday 1 January 2011

· Let there be light: One way to pump up your brainpower may be simply to sit in bright light for a few hours each day. People perform better in mental tests when ­under bright light. Photograph: Aaron Tilley for the Guardian

Have you woken up in 2011 vowing to cut down on your drinking, eat less and exercise more? All good basic principles, but research published in the past year has suggested that living a healthier lifestyle isn't quite so straightforward – and we needn't be quite so abstemious, either. There are plenty of less obvious, even counterintuitive, ways we can extend our lives and improve our health this year.

Don't diet too much: being slightly overweight is good for you

Until last year, the commonly accepted marker of a healthy weight-for-height was thebody mass index, or BMI: your weight in kilograms divided by the square of your height in metres. BMI charts originally identified 20-25 as the target range for the lowest risk of future ill health: below 20 and you were too thin; above 25 and you were overweight; above 30 and you were obese.

But that universally accepted standard changed in 2010. It seems a higher BMI score, of 25-27.5, is at least as healthy in terms of cardiovascular risk as one of 20-22.5. You really don't need to worry if you are a little overweight – provided you aren't more than around 5kg from the ideal weight for your height. The new emphasis is on waist measurements: men can be content if their waist is less than 38 inches and women should be happy with a waist of 34 inches or less. Keeping our waist measurements lower than those of our hips is a practical aim for everyone.

Exercise only in moderation

The two key terms for energy researchers in 2010 have been BDNF (brain-derived neurotrophic factor) and VEGF (vascular endothelial growth factor): BDNF stimulates the formation of new connections between brain cells; and VEGF produces new blood vessel-lining cells, potentially keeping the arteries free of flaws that are the potential sites of clots, and therefore preventing heart attacks and strokes.

Regular exercise increases levels of both, so it should be good for you – but there's a snag: too much exercise lowers BDNF levels. Does that have a damaging effect on brain cells? We don't yet know, but anecdotal evidence of the breakdown in health of athletes and enthusiasts who train to near-exhaustion every day tends to suggest that it does.

The main message, then, is to give your body time to recover after exercise. The current advice is to exercise to breathlessness (it doesn't matter what you do – anything you continue to enjoy) for around 30 minutes, and avoid exercising more than three or four times a week.

It's not how much fruit and veg you eat, but which type

According to American, Chinese and Finnish studies, eating lots of green, leafy vegetables helps to prevent type-2 diabetes, even if you don't lose weight in the process. Eating plenty of fruit and vegetables as part of a healthy diet also helps you avoid obesity, which has knock-on protection against heart attacks, strokes, diabetes and cancer. However, the big finding for 2010 was that particular foods can lower the rates of specific diseases. For example, alliums such as chives, leeks, shallots, onions and garlic are linked with much reduced rates of stomach and colon cancer, and it is claimed on good evidence (in the Journal of the National Cancer Institute) that tomatoes help to protect against prostate cancer. It seems cooking tomatoes, especially in olive oil, or eating them in ketchup, is even more effective than eating them fresh.

Get more light

One way to pump up your brainpower may be simply to sit in bright light for a few hours each day. Trends in cognitive sciences reported that people performed better in mental tests when under bright light, and other research journals have taken up the theme. The brighter the light, they have found, the more effective it is (pale blue light is even better). It seems that melanopsin, a newly discovered substance in the retina, absorbs the light and improves cognition.

Throw away your peeler

Skin, stalks and cores are all claimed to protect against cancer and boost nutrition. Now we come to something a little more contentious: today's buzzword is biosynergy, the theory that each part of a fruit or vegetable combines with the other parts to reinforce its nutritional benefit. Dr Marilyn Glenville, former president of the Food & Health Forum at the Royal Society of Medicine, says that discarding the skin of fruit isn't the only mistake we make. She recommends eating stalks and cores, too. The list of fruits she would persuade us to eat whole includes bananas – the peel is high in serotonin, needed in the brain to lighten mood and ease depression – and kiwi fruits, whose skin is high in antioxidants and is claimed to have anti-cancer, anti-inflammatory and anti-allergenic properties (golden kiwis have thinner, sweeter skins, so could be more acceptable eaten whole). She also advises eating the cores of pineapples, which contain twice the levels of bromelain, a digestive enzyme that protects the stomach lining, and orange and tangerine peel, which contain super-flavonoids that can significantly improve your lipid profile, theoretically improving your chances of avoiding a heart attack or stroke. Glenville recommends adding grated citrus peel to your food or putting the whole, unpeeled fruit into a juicer. As for vegetables, she claims that broccoli stalks contain more calcium, vitamin C and fibre than the florets, and that some vegetable skins may have anti-cancer properties, too. Garlic skin, for example, contains six separate antioxidant compounds, according to Japanese researchers. Glenville reccomends roasting garlic whole, along with other Mediterranean vegetables.

Know your alcohol limits

The news about health and alcohol isn't so surprising. Generally, we are drinking far more than any previous generation, and the troubles caused by our new habits are on the increase, from the social harm of drunken behaviour to the physical harm of failing livers and brains. Not only do we drink much more, but what we drink contains much higher levels of alcohol. Beers are stronger, while the alcohol content of wines has risen from around 8% abv to around 13% abv, and we drink them in 250ml rather than 125ml glasses.

So the message remains: women should stick to no more than two units a day and men could manage three, but shouldn't try. And make sure you know what a unit is. You may be surprised.

The idea that red wine has specific health advantages (because it contains the magic flavonoids) doesn't really hold up, either. Alcohol in small amounts does widen small arteries and helps smooth our blood vessel linings, in theory helping to prevent heart attacks and strokes. But to drink enough red wine to gain an advantage from its flavonoids would mean drinking more than is healthy. It is wiser to eat blueberries instead. According to recent research from Reading University, blueberries improve our attention levels and possibly our memories, too.

But there is some good news for pregnant women: one recent study says they can drink, entirely without guilt, up to two units a week.

Learn an instrument, at any age

For a long time, medical thought was that our brains were fully developed by our late teens, and that we started to lose neurones after that point. If we did keep on learning from then on, we were using nerves and pathways that were already established: we couldn't "grow" more neurones or connections. That is now in doubt. According to theEuropean Journal of Neuroscience, we may be able to train our brains to develop even once we are adults. It's more difficult than in childhood, but it does seem to work. Research done with London cabbies more than a decade ago provided evidence of new connections (for the purists, in the corpus callosum) between the two halves of the brain after they learned "the Knowledge".

What we now know is that professional musicians have the same expansion of the corpus callosum as did the taxi drivers. And that children who learn a musical instrument have more highly active brains than other children. The old claim that we use only a small part of our brain when we think or perform actions has been shown not to be true. Brain scans show that many areas of the brain light up when we perform the simplest of tasks, and that musical training improves and widens these connections. So become proficient in any instrument and you should improve your dexterity, intellectual capacity and resistance to age-related dementia. All pretty good aims for the year ahead.