FEELING extra tired or keep getting ill? You might not be eating enough protein.
And this could be putting you at risk of extreme swelling, bone fractures and even tooth loss, experts warn.
Dr Chun Tang, GP and medical director at , said: "Protein is like the building block for pretty much everything in your body - muscles, skin, hair, nails, even your hormones and enzymes.
"Without enough of it, your body can't repair cells, grow new tissues, or keep your immune system strong.
"Think of protein as the fuel that keeps your body functioning and resilient.
"Whether you're recovering from a workout, fighting off a cold, or just maintaining your muscle mass as you age, protein is key to keeping everything ticking along."
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Protein is found in larger quantities in foods like meat and dairy, as well as beans, nuts and eggs.
Exactly how much we need each day varies throughout our lives.
A child under three, for example, requires around 14g a day, whereas older people are advised to consume significantly more to prevent muscle wasting.
Generally though, the NHS recommends that people try to eat 0.75g of protein per kilogram of body weight every day.
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For the average woman, this is 45g, or 55g for men, which works out at about two portions of meat, fish, nuts or tofu daily.
"But if you're super active, pregnant, or trying to build muscle, you might need more - up to 1.2 to 2g per kilogram," Dr Tang said.
"Spread it out across meals for the best absorption."
If you stick to this guide (as well as eat a balanced diet full of fruits, vegetables and fibre), you should be providing your body with enough nourishment to build, maintain and repair cells and tissues.
You'll also be less likely to fall ill, and be quicker to recover.
But if you don't get enough protein, symptoms may begin to show - and you could face health complications down the line.
Dr Tang said: "There are definitely signs when your body is protein-deprived, and they’re not too subtle. Here are a few red flags."
1. Fatigue
If you've had a hectic week or been out partying, you might feel a little more tired than usual.
"But if you just can't shake that sluggish feeling, even after a good night's sleep, you might need to up your protein intake," Dr Tang said.
Jess Hillard, sports nutritionist at , added: "Persistent tiredness and low energy levels throughout the day, even after adequate sleep, can signal protein deficiency.
"This happens because your body isn't getting the nutrients needed to maintain energy levels."
2. Hair loss
"Notice more strands in the shower? Your hair may thin out because hair growth requires protein," the expert added.
And your skin can also take a hit, according to Jess.
"Thinning hair or dry, flaky skin may indicate a protein deficiency, as protein is essential for the production of keratin, which strengthens these tissues," she said.
3. Brittle nails
Another way protein deficiency can show is on your nails.
"If they chip easily or seem weaker, it’s a sign your body isn't getting what it needs," Dr Tang said.
4. Swelling
Low levels of protein can also cause swelling - especially in the legs and feet.
Known as oedema, this is due to fluid imbalances, Dr Tang said.
Jess added: "Protein helps regulate fluid balance.
"Swelling, particularly in the feet, ankles, or hands, may occur when your body lacks enough protein to maintain proper fluid distribution."
How much protein is actually in your favourite foods?
- Beef mince (140g) - 28g
- Battered cod (180g) - 25g
- Tinned tuna in oil (100g drained) - 25g
- Salmon (100g) - 23g
- Lamb chop (70g) - 20g
- Tofu (80g) - 19g
- Quorn (100g) - 13g
- Roasted peanuts (50g) - 13g
- Chicken breast (40g) - 11g
- Cheddar cheese (40g) - 10g
- Cow's milk (half pint) - 10g
- Soya milk (half pint) - 9g
- Baked beans (150g) - 8g
- Yoghurt (125g) - 7g
- Egg (one) - 7g
- Peanut butter (25g) - 6g
- Green lentils (40g) - 4g
Source: NHS
5. Weakness
Protein can help you build muscle, so it makes sense that not having enough of it can make you weaker.
"You may feel fatigued or struggle with physical activities that were previously easy," Jess said.
"Your muscles may also feel softer," Dr Tang added.
6. Ill often
Getting ill more than usual is another potential sign you need to eat more protein.
"Your immune system may struggle, making you prone to contracting frequent infections and getting sick more often," Dr Tang said.
7. Poor healing
Similarly, cuts or scrapes may take forever to heal.
"This is because protein is essential for tissue repair," he added.
8. Mood changes
From sleep deprivation to stress, there are numerous things that can affect your mood.
But one often-overlooked trigger is a lack of protein.
Dr Tang said: "Protein affects neurotransmitters, so you may feel more irritable or foggy without enough of it."
Jess added: "Protein is important for neurotransmitter production.
"Signs like irritability, mood swings, anxiety, or brain fog (difficulty concentrating or thinking clearly) can occur when you’re not getting enough protein to support brain function."
9. Always hungry
Jess said: "Feeling constantly hungry or experiencing intense cravings, especially for high-carb or sugary foods, can indicate you're not eating enough protein to keep your hunger hormones balanced."
10. Gum disease
And if that wasn't enough, protein deficiency can also increase your risk of gum disease.
Dr Rizwan Mahmood, dentist and co-founder of , said: "Not getting enough protein can affect your teeth and gums.
"Protein is key for keeping your mouth healthy.
"Your gums and the tissues that support your teeth rely on collagen, which your body makes from protein.
"Without enough protein, your body may struggle to produce collagen, leading to weaker gums and more risk of problems like gum disease."
It is, however, important to remember that these things can have other causes.
Dr Tang said: "They could be a sign of another health condition, so remember to speak with your doctor if you have any concerns."
High protein meal ideas
BREAKFAST
- Eggs (scrambled, poached, fried or omelette)
- Porridge made with milk, topped with nuts and seeds
- Granola or muesli with Greek yoghurt, nuts and seeds
- Peanut butter on whole grain toast
- Beans on toast
LUNCH AND DINNER
Include a portion or meat or plant alternatives at each meal, such as:
- Chicken breast
- Fish fillet
- Eggs
- Mince
- Tofu
- Beans
SNACKS
- Nuts and seeds
- Greek yoghurt or Skyr
- Cheese and biscuits
- Hummus with vegetables
- Boiled egg
DRINKS
- Milk
- Yoghurt-based drinks or smoothies
- Protein shake
Source: NHS
The dangers
Some of these symptoms can show relatively quickly.
"But not getting enough protein is more than just a short-term issue - it can cause some serious long-term health problems," Dr Tang said.
"You could lose muscle mass, which impacts your strength, metabolism, and overall mobility.
"Long-term protein deficiency can lead to conditions like kwashiorkor, which causes swelling, liver damage, and a weakened immune system.
"Plus, your bones can suffer because protein is important for bone health too - meaning you are at higher risk for fractures and osteoporosis.
"Protein is also vital for maintaining a healthy heart, so a severe lack of it can impact cardiovascular health."
Upping your protein game doesn’t have to be hard. If you’re pressed for time, there are easy options
Dr Chun Tang
Dr Mahmood added: "A lack of protein can also weaken your immune system, making you more prone to mouth infections like periodontitis, a severe form of gum disease that can cause tooth loss if untreated.
"Plus, if you get an ulcer, cut or sore in your mouth, low protein can slow down the healing process.
"While we often hear about calcium and vitamin D for healthy teeth, protein is just as important for keeping your gums strong and your teeth secure."
Take action
Thankfully, adding some extra protein into your diet isn't difficult.
And even a few simple swaps - such as natural yoghurt for Greek - could make a huge difference.
Dr Tang said: "Upping your protein game doesn’t have to be hard.
"Start by adding protein-rich foods to your snacks and meals.
"For example, mix some Greek yogurt into your breakfast or toss a handful of nuts onto your salad.
"Consider swapping out carbs for protein-based snacks like hummus and veggies or a hard-boiled egg.
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"If you’re pressed for time, a good-quality protein shake, or bar can help too.
"And don’t forget about plant-based proteins like lentils, quinoa, and beans - they’re excellent options for anyone looking to mix-up their protein sources."
Why is protein so important?
Mark Gilbert, nutritionist at by Cambridge Weight Plan, said: "Protein is perhaps the most important nutrient in our diets.
"Most of the dry weight of the human body is protein, including the skin, bones, muscles, blood, enzymes and hormones.
"Without optimum protein in the diet, we can’t build and repair muscle or bone, and our immunity, acid/base balance, fluid balance and ability to undertake thousands of other essential activities in the body will be compromised.
"We can live on a very small amount of fat per day, and carbohydrates are not essential in the diet at all, but without adequate protein, health inevitably declines.
"Signs of inadequate protein intake can fall into short-term and long-term problems.
"Initially, you may get weak, be more susceptible to infections, be hungry all the time, lose muscle and have poor recovery from injury or exercise.
"Also, since protein increases calorie expenditure much more than carbs and fat, the metabolism slows.
"Sometimes skin, hair and/or nail growth and appearance may be negatively affected.
"You also may become anaemic, particularly if you don’t eat adequate red meats.
"Because protein reduces hunger, increases the metabolic rate and increases muscle mass, not eating enough will increase the likelihood of weight and fat gain.
"More severe dangers from long-term under-consumption of protein include an increased risk of bone fractures, lower muscle mass, frailty and depression (all of which are more common in vegans).
"In the long term, very restricted protein intakes can also cause oedema and fatty liver disease, both associated with the disease kwashiorkor, which can be fatal but is usually not seen in affluent countries.
"If you think you may not be getting enough, choose quality proteins, which satisfy the body’s requirements at a lower intake of protein – so that’s meat, fish, eggs and dairy sources.
"Because of the protein leverage hypothesis and all of its benefits, we should all aim to have a substantial portion of quality protein at all of our meals and snacks.
"If you find this difficult, you can use a quality protein powder, like whey, casein, soy or pea protein and have a shake or add it to foods."