Doctor says don’t focus on calories only – try this for longevity

We all understand that ageing is inevitable, but that doesn’t stop us wanting to appear and feel younger. And whilst there’s no magic elixir of youth, there are ways to decelerate the ageing process and its impact on our looks and health, according to Dr Ian K. Smith.

In the Harvard-trained physician’s latest book, Eat Your Age, he states: “There’s so much you can do to keep yourself looking and feeling youthful, and it doesn’t depend on how much money you have or how many times you visit the plastic surgeon. 

“It’s about how well you plan, how aware you are of your body and health, and the simple steps you can take to forge a path of vigour and vitality that has nothing to do with the number of candles on your birthday cake.”

Dr Smith elaborates that his book is built upon the concept that the body’s nutritional, metabolic and medical needs evolve with age, and our eating habits must adjust accordingly.

Instead of offering a one-size-fits-all diet programme, he illustrates how to align food choices, physical activity, and preventative medicine with the specific demands of each phase of life.

“The goal is to help slow metabolic decline, preserve muscle, reduce chronic disease risk, and extend health span – not just lifespan,” he says. “Ultimately, it empowers people to take control of ageing through practical, science-based strategies that make longevity an intentional, achievable process.”

Focus on good fats, eat the rainbow

Adopt a more anti-inflammatory eating pattern emphasising omega-3 fats, colourful vegetables, whole grains and reduced added sugars, advises Smith. Digestive efficiency and insulin sensitivity often decline in the 50s, making food quality more important than quantity. “Inflammation – not ageing itself – is a major driver of chronic disease,” he warns.

Foods rich in antioxidants

Rooch rich in this can help protect blood vessels, joints and the brain. Hydration is also key as it helps ensure adequate protein intake, especially as thirst signals weaken with age. He also highlights the benefits of mindful eating and slower meal pacing for improved digestion and nutrient absorption.

Nutrition to support hormonal shifts

As metabolic rate begins to slow, protein becomes essential for preserving lean mass and managing appetite. Hormonal shifts, particularly in estrogen, testosterone, and cortisol, start to influence how the body stores fat and responds to stress

“It’s important to spread protein evenly across meals rather than concentrating it at dinner,” stresses Smith. “This supports muscle repair, stabilises blood sugar, and reduces late-night overeating.”

Additionally, monitoring portion sizes and cutting back on liquid calories becomes more critical, as your calorie requirements drop even when hunger levels remain unchanged.

Maintain cardiovascular fitness

Combine higher-intensity workouts with strength training, Smith recommends. Brief intervals of intense exercise help sustain cardiovascular health and combat age-related metabolic decline. Recovery matters more now,” he says. “Adequate sleep, mobility work, and rest days are essential to avoid burnout and injury.”

Your 30s

The decisions you make during your 30s subtly start to influence how you age, Smith points out. “While the body is still resilient, early metabolic shifts are already underway, making prevention far more powerful than correction,” he explains. “This is the time to build strong nutritional habits, consistent movement patterns, and medical awareness that will pay dividends for decades to come.”

Your 40s

Smith says the 40s represent a shift from building health to actively safeguarding it. Hormonal fluctuations and a gradual metabolic decline mean the body no longer reacts as it once did, even when habits stay the same. “This decade calls for smarter nutrition, more intentional exercise, and proactive screening to stay ahead of silent risks,” he says.

Your 50s

Throughout your 50s, health priorities shift from weight management towards building resilience, Smith explains. “Muscle loss, inflammation and chronic disease risk accelerate unless directly addressed through diet and movement. “The goal of this decade is to preserve strength, protect joints and bones, and maintain metabolic stability,” he explains. Focus on good fats, eat the rainbow.

Smith advises adopting a more anti-inflammatory eating pattern emphasising omega-3 fats, colourful vegetables, whole grains and reduced added sugars. As digestive efficiency and insulin sensitivity often decline in the 50s, food quality becomes more important than quantity.”

Your 60s – and beyond

The emphasis in your 60s and beyond moves from optimisation to preservation and targeted growth, according to Smith. “Daily habits now determine mobility, cognitive health and independence more than numbers on a scale. Eating well, moving consistently, and staying medically vigilant become the foundation for a longer, more vibrant life.”

Nutrition

Smith advises those in their 30s to shift away from merely counting calories and instead prioritise nutrient-dense foods, ensuring lean protein features in every meal, piling plates high with fibre-rich vegetables, and embracing healthy fats whilst reducing ultra-processed options.

“This decade is about preventing insulin resistance before it starts,” he says. Your metabolism is still relatively resilient, but subtle changes are occurring. Blood sugar regulation, cholesterol patterns and inflammatory markers can begin drifting in the wrong direction without obvious symptoms.

“This is why there should be an emphasis on eating for prevention, not correction,” he says. “Balanced meals that combine protein, fibre and healthy fats slow digestion, reduce blood sugar spikes, and support sustained energy throughout the day.”

Blood sugar control, cholesterol levels and inflammation markers can start creeping in the wrong direction without any obvious warning signs. “This is why there should be an emphasis on eating for prevention, not correction,” he says. “Balanced meals that combine protein, fibre and healthy fats slow digestion, reduce blood sugar spikes, and support sustained energy throughout the day.”

He cautions that whilst missing meals or depending too much on refined carbohydrates might not lead to instant weight gain, it paves the way for metabolic problems down the line.

Exercise goals

You should try and establish a consistent resistance-training routine (at least two to three days per week). “Muscle mass gained in your 30s becomes metabolic insurance later in life,” Smith explains. “Strength training improves insulin sensitivity, protects joints, and raises resting metabolic rate.”

Strength training should be paired with moderate cardiovascular activity – brisk walking, cycling, or swimming – to support heart health without excessive stress, he says.

Mobility work and strength training

Make strength training non-negotiable, while adding balance, mobility work, and exercises that challenge stability, such as single-leg movements. “Muscle loss accelerates during this decade if not actively resisted,” he warns.

Medical screening

You should also start routine bowel cancer screening discussions, and regular blood pressure, cholesterol and diabetes monitoring – particularly if there’s family history. The expert also stresses the importance of scheduling bone density testing, and screenings for cardiovascular disease, diabetes and cancer.

“Early detection dramatically improves outcomes,” he emphasises, adding that you should keep up with regular vision, hearing, cognitive, cardiovascular, and medication reviews. “These screenings protect quality of life and help preserve independence well into later years,” he added.

In addition, you should get baseline laboratory tests: fasting glucose, lipid panel, blood pressure, and waist circumference. “These markers create a personal health starting line and help identify silent risks early,” he explains.

Specific nutrient needs

Smith urges people to concentrate on sufficient protein, calcium, vitamin D and hydration levels, whilst moderating overall calories. “Appetite may decline, but nutrient needs remain high,” he says, highlighting that consuming insufficient protein is a common and dangerous error in older adults. Protein supports muscle strength, immune function, and recovery from illness. Meals should be simple, nutrient-dense, and easy to digest.”

Stay mobile to reduce risk of falls

You should focus on functional movement -strength, balance, flexibility, and walking. “The goal isn’t intensity, but consistency and safety. Regular movement preserves mobility, reduces fall risk and supports brain health. Even short daily sessions make a meaningful difference.”