What is the macro diet?

1. Carbohydrates (4 kilocalories per gram)

Carbohydrates are the body’s main source of energy. They’re broken down by the digestive system into glucose (sugar) before being absorbed into the bloodstream, from here the glucose can be used as ready energy or diverted to the muscles or liver for storage. We need carbs to fuel the body and to support the nervous system, kidneys, brain and muscles.

Carbs come in a variety of forms, the most common being sugars, starches and fibre, each of these has a different effect on your body. Starchy carbs found in foods like bread, rice, potatoes and pasta release glucose into the bloodstream more slowly than sugary foods and drinks.

Fibre is an important form of carbohydrate and vital for general health as it may help to reduce the risk of some diseases including bowel cancer, heart disease and type 2 diabetes. It also helps to promote digestive health and, having a low energy density, may help manage appetite.

Try these recipes for a healthy carbohydrate boost:

Oat & chia porridge
Baked jollof rice
Sweet and sour lentil dhal with grilled aubergine
Cod & olive tagine with brown rice

2. Protein (4 kilocalories per gram)

Protein is key to building and maintaining body tissues, such as muscles and is essential for a number of functions including growth, brain development, healthy bones and the production of hormones. Made up of ‘building blocks’ called amino acids of which there are 22 needed by humans, and nine that are termed ‘essential’ because we must obtain them from our diets.

We don’t typically use protein as a source of energy but we can do if we are not getting enough calories from carbs or from our energy stores. Using protein for energy can give you a slight calorie-burning edge, that’s because protein has a greater ‘thermic effect’ than either carbs or fat – what this means is to digest and absorb protein the body needs to use more energy. Adequate amounts of protein in the diet also promotes our sense of satisfaction.

Top sources of protein include meat, fish, eggs, soya products, nuts and pulses.

Try these recipes for a healthy protein boost:

Chicken satay salad
Pork souvlaki
Mexican chicken stew with quinoa & beans
Tofu curry

3. Fat (9 kilocalories per gram)

Fat, like carbs and protein, is needed by the body to build cell membranes, make nerve tissue and hormones, and aid the absorption of fat-soluble nutrients, including vitamins A and D. Our bodies use fat as energy and store any excess for future use; this stored fat acts as an insulator and helps cushion vital organs, bones and other tissues, protecting them from damage.
Although eating too much fat can be unhealthy, there are certain types of fat we must get from our diet because they’re essential to health.

Try these recipes for a healthy boost of fat:

Masala frittata with avocado salsa
Salmon salad with sesame dressing
Stuffed avocado with spicy beans & feta
Pesto chicken salad

How does the macro diet work?

There are many variations of the macro diet but they all involve classifying your calorie intake based on the individual macronutrients they are derived from – ie the number of calories from carbs, from protein and from fat.

How to calculate your macros

1. Work out your approximate calorie needs

2. Divide this calorie figure into proportions for each macronutrient, based on target percentages (see below)

3. Convert these targets into the number of grams of each macronutrient you need to eat to meet your calorie requirements

There is no consensus on what constitutes the ideal percentage split however, the following are common targets used by adopters of the macro diet:

• 30/30/40 - 30 per cent from protein, 30 per cent from fat and 40 per cent from carbs
• 40/40/20 - 40 per cent protein, 40 per cent carbs and 20 per cent fat
• 50/30/20 - 50 per cent from carbs, 30 per cent from protein and 20 per cent fat

How do I follow the macro diet?

Whichever split you adopt, you’re likely to need the help of a nutrition app. This will enable you to log and track your meals, and give you an understanding of the amount of protein, fat and carbs you’re eating and how they are contributing to your calorie intake.

It’s worth remembering that we are all unique and our individual needs vary based on our activity levels, gender, body weight and build, age and the existence of any medical conditions.

Read more about how to determine your calorie needs.

What foods should I eat on the macro diet?

All foods are allowed, as long as they fit within your macro targets, this for many followers is a refreshing change from the typical strict calorie control or elimination of entire food groups.

What foods should I avoid on the macro diet?

No foods are off limits, as long as they fit within your macro targets.

What’s the evidence for the macro diet?

There is limited evidence to support the macro diet, although there is evidence relating to diets that manipulate individual macronutrients such as a high-protein or low-carb diets, although there is less convincing support for a low-fat diet.

Will I lose weight on the macro diet?

Manipulating macronutrients, over a six-month period does appear to result in modest weight loss and has the potential to improve heart disease risk factors, especially blood pressure, however, by the 12 month point many of these effects are no longer visible.

Is the macro diet healthy? Our nutritionist’s view…

Although a macro diet focuses on counting macronutrients, these targets are based on a specific calorie range and as such the diet may be considered another form of calorie counting. Each of the macronutrients plays a unique role in our health and all are a source of energy. What constitutes the optimal balance, however, remains a long-standing debate.

The UK government recommends that for most people, 50 per cent of total dietary energy should come from carbs, with no more than 35 per cent from fat and no more than 11 per cent from saturated fat. There is no recommendation for protein, because although it provides some energy, it is not easily used by the body as a fuel source. That said, if you’re experiencing a prolonged calorie deficit or undergoing intense physical activity with your carb stores depleted, then the body will turn to protein to make up the shortfall.

This means there is no definitive macro split that may be considered optimal for health or for weight loss, and what works for you will be unique to your circumstances.

The macro diet does offer some flexibility and freedom for people to eat any food they wish as long as it fits within their macronutrient ratio and daily energy requirements.

Is the macro diet suitable for everyone?

There are some challenges with the macro diet that make it inappropriate for certain people, for example:

1. Precise calculations are required in order to track macros, which can be both time-consuming and frustrating, and may contribute to disordered eating behaviours.

2. Focusing solely on macronutrients may cause some to overlook the importance of micronutrients (vitamins and minerals). Though these are needed in smaller quantities in the diet, they're still vital for health.

3. Some individuals may need to count and adjust specific macronutrients, such as those with type 1 diabetes. People with type 1 diabetes – who need to be able to balance the amount of insulin with the carbs they eat – are typically offered support, supervised by a dietitian, on carb counting and how to keep their blood sugar levels within their target range.

4. Older adults, athletes and people with severe illness or at risk of malnutrition would need to ensure they have adequate amounts of protein. Older adults have higher protein requirements compared to their younger counterparts and the need for protein is increased with disease severity. For this reason, following the macro diet may not be appropriate for them.

Should I try the macro diet?

In general, everyone should aim to have a balanced and varied diet. Those who wish to embark on a macro diet should consult with a registered dietitian or nutrition professional to determine if it’s suitable for them, and to ensure their nutritional needs are being met.

Please note: if you're considering attempting any form of diet, please consult your GP first to ensure you can do so without risk to health.

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This article was reviewed on 15 December 2023 by Kerry Torrens

Tai Ibitoye is a registered dietitian and a doctoral researcher in food & nutritional sciences. Tai has experience working in different sectors such as in the NHS, public health, non-government organisations and academia.

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