Feeling tired all the time is usually caused by a mix of poor sleep, stress, low activity and diet, but it can also be a sign of a medical problem such as iron deficiency anaemia, vitamin B12 deficiency, an underactive thyroid, diabetes or depression. The NHS advises seeing a GP if you’ve been feeling tired for a few weeks and you’re not sure why, or if you have other symptoms such as weight loss or mood changes. Diet changes that often help include regular balanced meals, enough iron and B12, drinking enough water, and cutting back on alcohol and late caffeine.
Common everyday causes
- Not enough sleep, or poor-quality sleep. The NHS suggests aiming for 6 to 9 hours, with regular sleep times.
- Stress and busy lives, including caring for others or a new baby.
- Low mood or depression.
- Little physical activity. Regular activity often improves energy, even though it feels like the opposite when you’re tired.
- Diet: skipped meals, lots of sugary foods, too little iron or fluid, or too much alcohol and caffeine.
Medical causes to rule out
The NHS lists several medical conditions that can cause tiredness, including iron deficiency anaemia and thyroid problems, and warns against self-diagnosing. Others include:
- Iron deficiency anaemia: especially common in people with heavy periods, during pregnancy, and in people who eat little meat. The NHS lists tiredness among the main symptoms.
- Vitamin B12 deficiency: extreme tiredness is one of the symptoms listed by the NHS. It’s more common in older adults, vegans and people taking metformin or acid-reducing medicines.
- Diabetes: the NHS lists feeling very tired, very thirsty and peeing more often, especially at night, as warning signs.
- Sleep apnoea: loud snoring and pauses in breathing at night.
- Coeliac disease: tiredness can be a symptom, along with digestive problems, as the NHS explains.
A blood test can check for many of these. Don’t start iron or other supplements before seeing your doctor, because they can hide a problem or, in the case of iron, cause harm in people who don’t need it.
Eat for steadier energy
Regular meals
Long gaps between meals can leave you tired and irritable, and make you more likely to reach for sugary snacks. Try to eat breakfast, lunch and an evening meal, with a snack if you need one.
Balance each meal
Combine a source of protein, a fiber-rich carbohydrate and vegetables. Our guide to building a balanced meal shows how. Slow-release carbohydrates such as oats, whole grain bread, brown rice, beans and lentils give more even energy than sugary foods and white bread. Our guide to the glycemic index explains why.
Enough iron
Good sources include red meat, beans, lentils, tofu, fortified cereals and dark green vegetables. Vitamin C helps your body absorb iron from plant foods. Our guide to iron-rich foods lists the best sources.
Enough vitamin B12
Found in meat, fish, eggs, dairy and fortified foods. Vegans need a reliable source. Our guide to vitamin B12 explains who’s at risk.
Drink enough water
The NHS lists tiredness among the signs of dehydration. Our guide on how much water to drink explains how to tell if you’re getting enough.
Things that drain energy
Too much caffeine, too late
Caffeine can mask tiredness, but drinking it late in the day disturbs sleep, leaving you more tired the next day. The NHS suggests avoiding tea and coffee for at least 6 hours before bed if you have trouble sleeping. The FDA gives 400 mg a day as a limit for most healthy adults.
Alcohol
Alcohol may help you fall asleep, but it disrupts sleep later in the night, so cutting down often helps energy levels.
Energy drinks
They give a quick lift from caffeine and sugar, followed by a dip. They’re best avoided as a regular habit, and the American Academy of Pediatrics says energy drinks have no place in the diet of children and teenagers.
Very low-calorie diets
Eating too little can leave you tired, cold and unable to concentrate. If you’re trying to lose weight, a moderate approach is easier to stick with. Our guide on how many calories you need explains how to estimate yours.
Tiredness at different stages of life
- Teenagers need more sleep than adults, and teenage girls with heavy periods are at higher risk of low iron.
- Pregnancy often brings tiredness, especially in the first and third trimesters. Anaemia is also more common, so it’s checked with routine blood tests.
- Shift workers may need to plan meals around their shifts, with a main meal before work and lighter snacks during a night shift.
- Older adults are more likely to absorb less vitamin B12 and to eat less overall, so poor appetite and tiredness are worth mentioning to a doctor. Our guide to healthy eating for older adults has practical tips.
A day of eating for steady energy
| Meal | Example |
|---|---|
| Breakfast | Porridge with milk, berries and a spoonful of nut butter |
| Lunch | Lentil soup with whole grain bread and a side salad |
| Snack | A piece of fruit and a small handful of nuts |
| Evening meal | Salmon or tofu with brown rice and plenty of vegetables, eaten 2 to 3 hours before bed |
| Drinks | Water through the day; tea or coffee before early afternoon |
Our list of high-protein breakfast ideas has more morning options.
Common questions
Which foods give you energy fastest?
All foods provide energy, but sugary foods are absorbed fastest and can be followed by a dip. For steady energy, choose whole grains, beans, fruit, nuts and protein foods.
Can vitamins give me more energy?
Only if you’re deficient. If you’re tired, see your doctor for a blood test rather than guessing with supplements.
Why am I tired after eating?
Large meals, especially those high in refined carbohydrates or fat, can make some people feel sleepy. Smaller, balanced meals usually help. If you’re very tired after meals and also thirsty or peeing more, ask your doctor to check for diabetes.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
