Macros vs. micros – what are they and why are they important to athletes?

Macronutrients and micronutrients are categories that your dietitian or nutritionist may use when talking about your diet.  If you’ve ever spoken to anyone about diet in the sports industry, you will likely have heard the word “macros”. But what are they? And how do they differ from “micros”?

Think of macros and micros as the fuel and oil of your car. Macronutrients are the fuel – what keeps you going and gives you the energy to move. Micronutrients, on the other hand, are like the oil of a car – essential for keeping the body running smoothly.

In this blog we look at:

• Signs your nutrition might be holding you back
• What are macronutrients (macros)?
• Why are fats essential to athletes?
• Why is protein essential to athletes?
• Why are carbohydrates essential to athletes?
• What are micronutrients (micros)?
• Why are micronutrients important to athletes?
• The importance of monitoring macros and micros in performance

Signs your nutrition might be holding you back
 

Are you putting in the work, but not feeling the results? It could be that your nutrition plan needs some TLC.

Symptoms you may notice include:

• Needing longer recovery times
• Feeling fatigued, even after rest days
• Getting more colds or infections than usual
• Muscle aches, cramps, or injuries
• Training plateaus
• Irregular or missed periods

These symptoms can have many different causes, from overtraining to bad sleep. But it could also come down to nutritional deficiencies.

Low levels of B vitamins, vitamin D deficiency, or low iron are common for athletes, and inadequate intake of proteins, carbs, and fats, can leave you feeling flat.

In athletes, these symptoms can sometimes indicate low energy availability, where the body isn't getting enough energy to support both exercise and normal physiological functions. If prolonged, this can lead to Relative Energy Deficiency in Sport (REDs), affecting bone health, hormones, immunity and performance in both men and women. While a sports blood test could help you check for common deficiencies, persistent symptoms should be assessed by a healthcare professional rather than relying on blood tests alone.

 

What are macronutrients (macros)?
 

Macronutrients are nutrients needed in relatively large amounts. Carbohydrates and fats provide energy, while protein provides amino acids for tissue maintenance and repair and can also provide energy [1].

Macros include:

• Fats
• Proteins
• Carbohydrates

These macronutrients are an essential part of everyone’s diet, but why are they so important to athletes?
 

Why are fats essential to athletes?
 

Fats are often perceived as a food group that you should either cut out or restrict. However, fats are necessary for important bodily functions. It is recommended that dietary fats make up 20-35% of your diet [2].

Fats help your body absorb important micronutrients such as fat-soluble vitamins. Ensuring these vitamins are absorbed into the body is vital for proper bodily functions.

Omega-3 fatty acids, a type of polyunsaturated fat found in oily fish, walnuts, and flaxseeds, are particularly beneficial for athletes. They can help reduce inflammation, support joint health, and may aid in muscle recovery after intense exercise.

Unsaturated fats include:

• Olive oil
• Avocado
• Nut butter
• Oily fish

Unsaturated fats can also help your body with [2]:

• Blood lipid management
• Support for normal physiological functions
• Inflammation control
• Potential body composition and performance benefits

Therefore, cutting out fats from your diet can be detrimental to not only your performance but also your overall health.

Different dietary fats have different health effects. Unsaturated fats are generally preferable to saturated fats, while industrially produced trans fats should be avoided.

The advice for saturated and trans fats is to keep your intake as low as possible, as they can increase cholesterol levels and heighten the risk of diseases such as cardiovascular disease [3]. These fats are often found in ultra-processed foods such as biscuits, crisps, and cakes.

Ensuring your recommended allowance of 20-35% fats is included in your diet can help you to stay healthy, but also:

• Help with body composition (and get you competition-ready)
• Boost energy levels for better performance
  
   

Why is protein essential to athletes?
 

Whether you are running, swimming, or strength training – when you’re an athlete you use more energy than the average person and therefore need added nutrients to recover. And protein is the macronutrient the sports world constantly talks about. But why?

Dietary protein is digested into amino acids that the body uses to build and repair tissues, including muscle, skin and hair  [4].
 

What is the recommended amount of protein?
 

The UK reference nutrient intake for adults is approximately 0.75g of protein per kilogram of body weight daily. Many athletes benefit from around 1.2–2.0g/kg/day depending on their training and goals. Distributing protein across meals can help support muscle protein synthesis.

There is not official upper limit for protein but according to the British Heart Foundation, eating more than 2g per kilo of body weight may put strain on your kidneys - especially if you already have a kidney problem. It's also worth varying your protein sources rather than relying on red and processed meat such as bacon and steak [4].

Non-meat sources of protein include [6]:

• Beans and pulses
• Quinoa
• Nuts and seeds
• Quorn
• Tofu
• Eggs and dairy such as milk, yoghurt and cheese

This is not to say you need to cut out meat completely, but getting more varied sources of protein can help boost your protein intake and help aid recovery - resulting in long-term progress and performance.
 

Why are carbohydrates essential to athletes?
 

Like fats, carbohydrates are often seen as a food group that should be restricted when it comes to weight loss or sports performance. However, cutting out carbohydrates (carbs) can lead to a variety of unwanted side effects.

Side effects of cutting out carbs include:

• Lack of energy or fatigue
• Constipation
• Headaches
• Muscle cramps

All of which can reduce your athletic performance. Carbs often have a stigma attached to them of making you feel stodgy or bloated, however, they could be the key to you winning a race or recovering faster.

Carbohydrates are vital in the production of energy and are a key energy source during exercise. If your body doesn’t have the energy to fuel it, your performance is bound to take a hit.

Not only are they important for giving you the energy you need to perform, but they also work alongside protein to help optimise recovery.

Fibre, a type of carbohydrate that the body cannot digest, is also crucial for athletes. It supports digestive health, helps regulate blood sugar levels, and can contribute to a feeling of fullness, which may help with weight management. Good sources of fibre include whole grains, fruits, vegetables and legumes.

If the thought of carbs is making you feel bloated, maybe it’s time to mix up your sources – carbs don’t always mean bread and pasta.

Good sources of carbohydrates for athletes include:

• Oats
• Lentils
• Nuts
• Blueberries
• Brown rice
• Sweet potatoes
• Oranges

The amount of carbohydrate you need depends on how much you train.

Recommendations range from around 3–5g per kilo of body weight a day for lighter training, up to 8–12g for very high-volume endurance training [2]. It can help to eat more carbs on hard or long training days and fewer on rest days.

The importance of macronutrients in sports performance is that they provide energy and optimise recovery. But how do micronutrients play a part?
 

What are micronutrients (micros)?
 

Micronutrients are better known as vitamins and minerals, and we get almost all our micronutrients through diet. The main exception is vitamin D, most of which our skin makes from sunlight.

They are needed in very small amounts but help almost every process in the body, including:

• Immune function
• Bone health
• Blood clotting
• Energy production
• Fluid balance

Micronutrients can be split into four main groups, outlined below [8].

1. Water-soluble vitamins

The majority of vitamins can be dissolved in water and are often not stored in the body (any excess will be flushed out in urine). The exception is B12, which the liver can store for years. These vitamins play an important role in energy production, and it is important to get them from a variety of food sources.

Water-soluble vitamins include:

• Vitamin C
• Folate (vitamin B9)
• Vitamin B12
• Biotin (vitamin B7)

Staying well hydrated is important too. The NHS recommends that everyone should drink six to eight glasses of fluid a day. However, when exercising you may need to drink more to compensate for any fluid loss through bodily functions such as sweating.  In fact, drinking before, during, and after exercise will boost your energy levels, and may help to prevent muscle cramps.

2. Fat-soluble vitamins

Fat-soluble vitamins don’t dissolve in water and are stored in the liver and fatty tissues for future use.

Fat-soluble vitamins play a vital role in the proper function of:

• The immune system
• Bone development
• Vision
• Protection of cells

Fat-soluble vitamins include [2]:

• Vitamin A
• Vitamin D
• Vitamin K
• Vitamin E

If you don’t eat enough fats, these fat-soluble vitamins may not be absorbed properly and you may be left with a deficiency, which can cause some unwanted symptoms.

Symptoms of a fat-soluble vitamin deficiency include:

• Problems with vision
• Skin irritation
• Bruising easily
• Bone pain and muscle weakness

Include certain types of fats in your diet (such as unsaturated fats) to reduce the risk of becoming deficient in these vitamins.

Vitamin D deficiency can affect bone and muscle health. In the UK, sunlight is generally insufficient for reliable vitamin D synthesis during autumn and winter. The NHS recommends that everyone considers a daily supplement containing 10 micrograms (400 IU) of vitamin D between October and early March [8].

Not sure what your levels are? A simple blood test like our Vitamin D Blood Test can be taken from the comfort of your home, and help you figure out if you need a vitamin D supplement, as per the NHS guidelines.

3. Macrominerals

Macrominerals are required in higher amounts than trace minerals and can be found in everyday foods and multivitamins.

Macrominerals include:

• Calcium – important in the structure and function of bones
• Magnesium – supports muscle function and helps in energy production
• Sodium – helps regulate fluid balance and is lost when sweating
• Potassium – vital in muscle function

Being deficient in any of these macrominerals can affect your training. Ensuring you have the right amount of these minerals can make all the difference in helping you achieve your goals.

4. Trace minerals

Trace minerals are required in small amounts, but that does not mean they aren’t important.

Trace minerals include:

• Iron
• Zinc
• Iodine

Iron deficiency is common in athletes, particularly women, endurance runners and those following plant-based diets.

If you are short on iron, it can hugely affect your ability to perform at your best as it is heavily tied to your oxygen carrying capacity and aerobic performance. An Iron Study test looks at all your iron markers, including ferritin, which is a good measure of your iron stores themselves.  
 

Why are micros important to athletes?
 

The micronutrient content of food varies, so you need a wide variety of food to meet your requirements. Marginal deficiencies may have little effect on a sedentary person but could have significant effects on an athlete.

It is also possible that regular, intense exercise may increase micronutrient losses from the body, making it important for athletes to meet their micronutrient intake requirements.

If you take part in regular sports, when looking at dietary intake and fuelling, it’s common practice to focus on energy intake and macronutrients. However, despite the fact we need them in smaller amounts compared to macronutrients, micronutrients are vital to our performance and health.
 

The importance of monitoring macros and micros in performance
 

The importance of macros and micros is obvious – they help fuel the body, keep it running smoothly, and ensure optimal health and performance. But, how do you know if you are getting the right amounts?

Selected blood tests, like those in Sports Performance collection, can help investigate problems such as low iron stores or vitamin B12 deficiency and measure other health markers, including lipids, red cells and hormones too.

However, blood tests alone cannot establish whether you eat enough calories, protein or carbohydrate, and hormone results do not independently determine your nutritional needs. Your symptoms, dietary intake and training demands are equally important when assessing sports nutrition and go hand in hand with our tests.

If you are unsure which test is the right one for you, see our sports performance buying guide, or try our test finder.

---

References

1. British Heart Foundation. What are macronutrients? [Internet]. London: British Heart Foundation; 2022 [cited 2026 Sep 24].
2. Lowery LM. Dietary fat and sports nutrition: a primer. J Sports Sci Med. 2004;3(3):106–117.
3. European Food Information Council. The functions of fats in the body [Internet]. Brussels: EUFIC; 2015 [cited 2026 Sep 24].
4. British Heart Foundation. Protein: what you need to know [Internet]. London: British Heart Foundation; 2022 [cited 2026 Sep 24].
5. British Heart Foundation. How to get protein without the meat [Internet]. London: British Heart Foundation; 2022 [cited 2026 Sep 24].
6. Wildman R, Kerksick C, Campbell B. Carbohydrates, physical training, and sport performance. Strength Cond J. 2010;32(1):21–29.
7. National Research Council (US) Committee on Diet and Health. Diet and health: implications for reducing chronic disease risk. Washington (DC): National Academies Press (US); 1989. doi: 10.17226/1222
8. NHS. Vitamin D [Internet]. NHS; 2020 [cited 2026 Sep 24].