Dr Ian K Smith says our eating habits need to evolve with our bodies
Eat Your Age(Image: PA Media)
We all know getting older is unavoidable, but that doesn’t mean we don’t want to look and feel more youthful. And while there’s no magical fountain of youth, there are methods to slow the ageing process and its effects on our appearance and wellbeing, according to Doctor Ian K. Smith.
In the Harvard-educated doctor’s new book, Eat Your Age, he says: “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.“
Smith explains his book is founded on the principle that the body’s nutritional, metabolic and medical requirements change with age, and our dietary patterns need to adapt accordingly. Rather than presenting a universal diet plan, he demonstrates how to match food selections, exercise, and preventative healthcare with the particular requirements of each life stage.
“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.”
Your 30s: Decisions that determine future wellbeing
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.”
Nutrition for prevention
Smith recommends those in their 30s move away from simply counting calories towards focusing on nutrient-rich foods, making lean protein a staple at each meal, loading up on fibre-packed vegetables, and incorporating healthy fats whilst cutting back on ultra-processed fare.
“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.
Set consistent exercise goals
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.
Your 40s: Strategic maintenance and metabolic protection
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.
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 50s: Preserving strength, reducing inflammation
During your 50s, health shifts from being about weight to focusing on 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
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
These help protect blood vessels, joints and the brain. Hydration remains as critical as 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.
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
Get baseline laboratory tests: fasting glucose, lipid panel, blood pressure, plus waist circumference. “These markers create a personal health starting line and help identify silent risks early,” he explains.
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,” says Smith.
You should also start routine bowel cancer screening discussions, and regular blood pressure, cholesterol and diabetes monitoring – particularly if there’s family history.
He also stresses the importance of scheduling bone density testing, and screenings for cardiovascular disease, diabetes and cancer. “Early detection dramatically improves outcomes,” he emphasises.
Your 60s and beyond: Sustaining independence and quality of life
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.”
Specific nutrient needs
Smith advises concentrating on sufficient protein, calcium, vitamin D and hydration, 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
Focus on functional movement -strength, balance, flexibility, and walking. “The goal isn’t intensity, but consistency and safety,” says Smith.
“Regular movement preserves mobility, reduces fall risk and supports brain health. Even short daily sessions make a meaningful difference.”
