How to eat healthily in every decade of your life

Certain decades of life and the changes they bring, be they hormonal or lifestyle-based, can require us to sharpen our focus on particular areas. Photo / Getty Images

Part of the Telegraph's guides to better health and wellbeing throughout your lifetime, experts reveal how to maintain a healthy diet with body-boosting foods, whatever your age.

Eat well while you're young, and you'll set up healthy habits for life - a good idea in theory, certainly, though trickier in the offing. While the mainstays of a good diet apply no matter your age - everything in moderation, eating whole foods wherever possible and choosing from a wide range of ingredients - certain decades of life and the changes they bring, be they hormonal or lifestyle-based, can require us to sharpen our focus on particular areas. Here's what to look out for at every age and stage.

Teens

Calcium maintenance at this age matters to develop bone mass for later life. Photo / Getty Images

Your metabolism slows with age – a decline that begins, according to Michael Jensen, who researches the subject at the Mayo Clinic, at the age of 18. While there may be no better time for us to be laying the groundwork for good eating patterns, however, this is surely when we are least likely to do it, as the sweet counter at the newsagent and sneaky trips to McDonald's after school so often prove more alluring than the broccoli parents optimistically load onto their adolescents' plate at dinner.

"It's a generation we're a bit worried about," says dietitian Helen Bond, pointing to the low-iron diets teenagers, who often choose ultra-processed foods, are subject to. The requisite amounts –11.3 - 14.8mg per day for boys and girls respectively – from foods such as red meat, leafy greens and wholegrains will safeguard growth and muscle development while warding off "poor lethargy and concentration."

Girls' requirements are the larger, due to blood loss during menstruation: haem iron is the form most efficiently absorbed by the gut (and found in meat and fish), though a well planned vegetarian diet of non-haem iron-rich foods such as vegetables, cereals and pulses can produce the same results.

Calcium maintenance at this age matters as well, adds Bond. "Teenagers don't really think about how they will be in their sixties and seventies because it's a long way off, but bone mass is attained within [those] years," she says.

Research shows that 16 per cent of teenagers overall (or 22 per cent of girls aged 11-18) fall short of the recommended amount of 800-1000mg per day, the best sources of which are in dairy products like milk, cheese and yogurt, and leafy greens, pulses and fish (particularly those with bones in, like sardines). "Good foundations really are key," Bond says. "The more calcium that's deposited in the bones during childhood and adolescence, the stronger bones will be in later life."

Twenties

Avoid fad diets in your 20s: a 2014 study found that enacting extreme weight-control methods now led to a greater likelihood of being overweight or obese by the time they reached their thirties. Photo / Getty Images

Student life, personal relationships and career-building can easily get in the way of good living, yet healthy habits instituted during your twenties will have a lasting effect: a 2012 study found that those who maintained good eating and fitness regimes during this age had a lower risk of heart disease in their 40s, irrespective of whether it ran in their family – proof that nurture may well be able to override nature.

But late nights in the office often end up in the pub, and then the kebab shop; youthful metabolism may still be on your side to a degree, but that can only last so long. Finding love can have a pernicious effect on your waistline, too: a study of 2000 people last year found that an average of 1.2 stone was gained in the first year of coupling up, with that more than doubling to 2.6 stone over the course of a relationship.

And attempting to counteract additional pounds with fad diets, also commonplace during one's twenties, do little good either - a 2014 study found that enacting extreme weight-control methods now led to a greater likelihood of being overweight or obese by the time they reached their thirties.

"Males are very simple creatures - we are born, we think about food, and that's it," says Dr GIles Yeo, Principal Research Associate at the University of Cambridge and author of Gene Eating. For women, he adds, things are more complex: "there are four types: pre-baby, pregnant (an entirely different species), post pregnancy and post menopause. The huge changes in hormones influence the entire landscape in which the foods interact."

The best means of defence is, he says, "keeping in mind the rules of moderation" and ensuring a diet rich in "fibre, which keeps our microbiome and bowel happy, and more unsaturated fats (i.e. avocados and oily fish) rather than saturated ones (such as processed meat and butter) - those are two golden rules."

The trend for 'clean eating', or cutting out entire food groups like carbohydrates or fat in order to keep weight at a stable level, also has poor outcomes for longterm health too, Dr Yeo says, adding that the real secret to good living "is the most boring in the world – a moderate amount of everything."

Keep an eye on sugar and fat consumption, he adds, but "don't demonise any foods," as this will only create deficiencies further down the line or bad habits for when short-term diets – the majority of which fail – veer off-course.

Thirties

Stress is one of the biggest causes of weight gain during this age and, as workplace pressures and the need to balance the personal and professional rise during this time of life. Photo / Getty Images

Eating for two may sound exciting in theory, but is just one of many medical myths surrounding pregnancy, says Hollywood fitness instructor Simone De La Rue. "You will have cravings and that's natural" – she admits that pizza and ice cream featured among hers – "but like anything, you have to have discipline," she explains.

The UK's NHS makes similar warnings about the dangers of "eating for two", encouraging expectant mothers to maintain healthy levels of fruit, fat and fibre, while avoiding mould-ripened soft cheeses (such as brie or camembert), too much oily fish (no more than two portions per week), and partially cooked meat or eggs.

Stress is one of the biggest causes of weight gain during this age and, as workplace pressures and the need to balance the personal and professional rise during this time of life, recognising the signs it may be derailing your diet are key. Being consumed with work can cause either disaffection with ensuring that you are eating right or cause you to reach for options that are low in nutrients but high in saturated fats "in an attempt to fulfil emotional needs," according to the Mayo Clinic, "even when you're not hungry."

They advise asking yourself why you're eating before that first bite: is it because your stomach really is rumbling, or just because you want the warm embrace of slab of Dairy Milk? Stress also directly affects the speed of women's metabolism, according to 2015 research, with study participants who admitted to feeling under pressure in the 24 hours prior burning fewer calories than their peers, as well as resulting in higher levels of insulin, which contributes to fat storage - usually around the abdomen, which is linked to far greater health risks.

Forties

In your 40s, you'll likely find yourself with more time and money to spend eating. Photo / Getty Images

Middle age sees a "toxic mixture of sitting down all the time and having a lot of money to spend on food," Dr Yeo says, "and if you are at risk of type 2 diabetes or cardiovascular disease, you need to watch what you eat.

"There's a huge chunk of the population for whom diet related illness are driven by lifestyle, and they make themselves most apparent" at a time when "the bounciness of youth" has departed, and four decades of damage accumulation make themselves known.

Dr Yeo's preferred method for "keeping the tide back" is to ensure good levels of physical activity (if you haven't already) which will not only keep middle aged spread in check, but combat diminishing muscle mass. Sam Gregory, co-founder of F45 Stratford fitness studio, suggests "two good resistance training sessions and two cardio" weekly, complemented by "plenty of healthy fats – nuts, seeds and good quality oils including olive, coconut and avocado."

Gregory, 41, also takes a fish oil supplement, which "tends to help with cardiovascular health," while opting for protein-based breakfasts instead of more carbohydrate-heavy toasts and cereals; "changes that will really help the body."

Fifties

Eating well and moving as much as possible must override the natural inclination to take your foot off the pedal. Photo / Getty Images

The average woman in the UK begins the menopause at 51 (52 in New Zealand), at which point oestrogen production drops, raising heart disease risk to the same level as men's, as well as susceptibility to osteoporosis. Weight, blood pressure and cholesterol must be monitored during this decade, which means cutting back on alcohol and caffeine, and picking low-sodium options where available for foods like stock cubes, baked beans and soy sauce at the supermarket.

With evermore research drawing links between our lifestyles and serious diseases like cancer, inflammation and hypertension, renewed focus on eating well and moving as much as possible must override the natural inclination to take your foot off the pedal.

"Life expectancy would grow by leaps and bounds if green vegetables smelled as good as bacon," journalist Doug Larson once wrote: both as a prescient nugget of truth, and reminder that processed meats like those found in a BLT serve, sadly, very little nutritional purpose.

Sixties and Seventies

As life expectancy increases, ensuring that the growing number of years we have are good quality matters all the more. Photo / Getty Images

Retirement can provide a good point at which to recalibrate healthy regimes. Continuing a diet rich in calcium and protein sources remains crucial, due to the ongoing diminishment of bones and muscle: Bond advises plenty of kale, spinach, broccoli, eggs and brightly coloured fruits.

The latter, including oranges and carrots, are rich in carotenoids lutein and zeaxanthin, which are believed to boost eye health generally and protect against conditions like age-related macular degeneration, which can impair vision.

With life expectancy in the UK now 81, ensuring that the growing number of years we have are good quality matters all the more. At every stage, "you need to find a diet and exercise regime – it's not one versus the other – that matches your age in life," Dr Yeo advises.

Maintenance may not feel as immediately gratifying as shedding half a stone thanks to a rapid diet, but the longterm benefits of sustained good living mean you will see the proof in the (occasional) pudding.