Diet and fitness: what actually matters
You can't out-train a poor diet. For most people, what you eat drives body composition more than exercise alone. The fundamentals are simple and boringly effective: eat mostly whole foods, get enough protein (roughly 1.2–2.0 g per kg of body weight if you're active), fill half your plate with vegetables and fruit, favour whole grains over refined ones, and keep highly processed food and sugary drinks occasional rather than daily. Weight change comes down to energy balance — eating a little less than you burn to lose fat, a little more to build — but how you do that determines whether it lasts. Crash diets and extreme restriction almost always rebound; sustainable, modest changes win.
Eating for your blood type
The "blood type diet," popularised in Eat Right 4 Your Type, claims your ABO blood group determines which foods suit you. It's a popular idea, so here's what it recommends — followed by an honest note. Important: high-quality research has not found that blood type affects how you respond to food. People who follow it often feel better mainly because it cuts processed junk, which helps anyone. Treat the table below as the diet's framework, not established science.
| Blood type | Favours | Limits | Sample day |
|---|---|---|---|
| Type O | Lean meat, fish, vegetables, olive oil | Wheat, corn, most dairy | Eggs & spinach; grilled salmon & broccoli; steak & roasted vegetables |
| Type A | Vegetables, tofu & soy, seafood, whole grains, fruit | Red meat, dairy | Oatmeal & berries; lentil & vegetable soup; tofu stir-fry with brown rice |
| Type B | A varied mix: meat, dairy, seafood, grains, greens | Chicken, corn, peanuts, wheat | Yoghurt & fruit; lamb & green salad; fish with quinoa and vegetables |
| Type AB | Seafood, tofu, dairy in moderation, grains, fruit, vegetables | Chicken, cured meats, caffeine, alcohol | Eggs & greens; tuna salad; tofu & vegetable curry with rice |
Notice the overlap: every version tells you to eat more vegetables and whole foods and less processed food. That's the part that genuinely works. If you enjoy the structure of eating for your type, there's no harm in it as long as the result is balanced — just don't expect blood type itself to be the magic. The best-evidenced pattern remains a Mediterranean-style diet: vegetables, fruit, whole grains, legumes, fish, nuts and olive oil.
How often should you eat?
There's no single right answer. Three balanced meals a day, with one or two snacks if you're hungry, works well for most people. What matters more than frequency is total intake and food quality. Eating regularly helps steady energy and stops the ravenous over-eating that skipping meals can trigger. Some people do well with intermittent fasting (eating within a set window), but it isn't necessary or better for everyone, and it's not suitable during pregnancy, for growing teens, or for anyone with a history of disordered eating. Prioritise protein and fibre at each meal to stay full, and don't drink your calories.
How much water should you drink?
A practical rule is about 30–35 ml of water per kilogram of body weight per day. Needs are higher per kilogram for children and a little lower for older adults. Roughly 20% comes from food, and you need more with exercise, heat, pregnancy or illness — add about 500 ml per hour of moderate sweating. Your kidneys can only handle about a litre an hour, so sip through the day rather than gulping large amounts at once.
| Group | Rough daily fluid target |
|---|---|
| Children 1–3 yrs | ~1.3 litres |
| Children 4–8 yrs | ~1.7 litres |
| Children 9–13 yrs | ~2.1–2.4 litres |
| Teens 14–18 yrs | ~2.3 litres (girls) to 3.3 litres (boys) |
| Adult women | ~2.7 litres total (about 2.1 L as drink) |
| Adult men | ~3.7 litres total (about 3.0 L as drink) |
| Adults 65+ | ~25–30 ml/kg — thirst declines, so drink on schedule |
Totals include fluid from all drinks and food. The simplest daily check is your urine: pale straw colour means you're well hydrated; dark yellow means drink more.
Lose weight at home — no machines needed
You don't need a gym or equipment to get fit. Bodyweight training builds real strength and, combined with a calorie-aware diet, is very effective for fat loss. The key is intensity and consistency, not fancy kit. Core moves: squats, lunges, push-ups, planks, glute bridges, mountain climbers, jumping jacks, high knees and burpees.
A simple starter circuit: do each move for 40 seconds, rest 20 seconds, run through the list twice, three to four times a week — squats, push-ups, mountain climbers, glute bridges, jumping jacks, plank. That's about 20 minutes. Add a brisk daily walk, and you have a complete, free programme. Progress by adding rounds, slowing the lowering phase, or shortening rest as you get fitter.
Exercise by age group
| Age group | Recommended activity |
|---|---|
| Children & teens (5–17) | At least 60 minutes a day of mostly aerobic activity, plus muscle- and bone-strengthening play (running, jumping, climbing) three days a week |
| Adults (18–64) | 150–300 minutes of moderate, or 75–150 minutes of vigorous, aerobic activity per week, plus strength training on two or more days |
| Older adults (65+) | The same as adults where possible, plus balance and strength work three days a week to protect against falls |
These are World Health Organization targets. Any movement beats none — if you're starting from zero, begin with short walks and build up. Something you'll actually do beats a perfect plan you won't.
Exercise during and after pregnancy
For most healthy pregnancies, staying active is beneficial for both mother and baby, but this is the one area where you should get your doctor's or midwife's go-ahead first. General guidance is around 150 minutes of moderate activity a week, spread across the week. Good options are walking, swimming, stationary cycling, prenatal yoga and light strength work; pelvic-floor (Kegel) exercises help throughout and afterwards. Avoid contact sports, activities with a fall risk, lying flat on your back after the first trimester, and getting overheated. Stop and seek advice if you have bleeding, dizziness, chest pain or contractions.
Getting back in shape afterwards: start gently and only once your doctor has cleared you — usually around the six-week check, later after a caesarean. Begin with walking and gentle pelvic-floor and deep-core work rather than crunches, since the abdominal muscles often separate during pregnancy (diastasis recti) and need careful rebuilding. Build intensity gradually over months, not weeks, and be kind to yourself — recovery is not a race.
Staying fit at a desk job
Sitting for hours is its own health risk, separate from whether you exercise. If you work at a desk, the single best habit is to break up sitting every 30–60 minutes — stand, stretch or walk for a few minutes each hour. Aim for 7,000–10,000 steps across the day. Desk-friendly moves you can do without changing clothes: calf raises, chair squats, seated leg raises, glute squeezes, shoulder rolls, neck stretches, and standing or walking during phone calls. Take the stairs, park further away, and use part of your lunch break for a short walk. A walking meeting or a standing desk turns dead time into movement.
Free apps to help you stay in shape
- Nike Training ClubGenuinely free with no in-app purchases — hundreds of guided strength, cardio, yoga and mobility workouts, many with no equipment.
- FitOnFree access to a big library of guided workouts (HIIT, yoga, pilates, dance, strength) with trainer-led videos.
- Adidas TrainingBodyweight-focused plans that adapt to your progress — great for training with no gear.
- Down DogGenerates a fresh yoga class each time based on your level, length and focus; strong free tier.
- 7 Minute WorkoutShort, science-based circuits for busy days — minimal space, no equipment.
- StravaFree tier for tracking runs, rides and walks, with routes and a motivating community.
- HevyClean, free workout logging for anyone following a strength programme.
App details and free tiers change, so check the current version before subscribing to anything — the free options above are enough for most people to train well.
How fitness helps the brain
Exercise is one of the most powerful things you can do for your mind, not just your body. Physical activity increases blood flow to the brain and raises a protein called BDNF (brain-derived neurotrophic factor) that helps grow, connect and protect neurons — especially in the hippocampus, the region central to memory and learning. The practical effects are well documented: better memory and focus, faster thinking, improved mood, and meaningfully lower rates of anxiety and depression. Over a lifetime, regular exercise is one of the strongest known protectors against cognitive decline and dementia. Aerobic activity shows the biggest brain benefits, but any consistent movement helps.
Sleep, fitness and brain health
Sleep is where training actually pays off. During deep sleep your body releases growth hormone and repairs muscle, which is why recovery — not the workout itself — is when you get stronger. Sleep also regulates the hunger hormones leptin and ghrelin, so poor sleep tends to increase appetite and cravings, working against weight goals. For the brain, sleep consolidates memories and clears metabolic waste through the glymphatic system; chronically short sleep impairs focus, reaction time, mood and decision-making. Most adults need 7–9 hours. If you train hard but sleep badly, you're leaving most of the benefit on the table. Protect sleep like you protect your workouts: consistent timing, a dark cool room, and less screen time before bed.
Frequently asked questions
How do I calculate my running pace?
Divide total time by distance. Running 5 km in 25 minutes is 5:00 per km (about 8:03 per mile). The Pace tab does the conversion and gives your speed.
How many calories do I burn exercising?
It depends on the activity, your weight and duration — roughly MET × weight in kg × hours. Running burns about 600–800 an hour for an average adult, brisk walking around 300. The Cal Burned tab estimates it.
How much water should I drink a day?
About 30–35 ml per kg of body weight — roughly 2.1–2.4 litres for a 70 kg adult — plus more for exercise, heat or pregnancy. Children need more per kg, over-65s a little less. Pale urine means you're well hydrated.
What exercises can I do at home without equipment?
Squats, lunges, push-ups, planks, glute bridges, mountain climbers, jumping jacks and burpees. A 20-minute circuit a few times a week, plus a daily walk and a sensible diet, is a complete free programme.
Does the blood type diet actually work?
There's no solid evidence that blood type changes how you respond to food. People lose weight on it mainly because it cuts processed junk. A balanced, mostly whole-food or Mediterranean pattern is what the science supports.
How does exercise help the brain?
It boosts blood flow and BDNF, a protein that grows and protects brain cells in the memory-related hippocampus. The result is better memory, focus and mood, less anxiety and depression, and lower dementia risk. Aerobic exercise helps most.
Everything here is general education, not medical advice. Consult a doctor or qualified professional before making significant changes to diet or exercise, especially during pregnancy, after birth, or with any health condition. Calculator results are estimates.