What is protein and why do we need this for health and well-being?
With the modern world and a range of convenience foods, it’s become difficult to know what is a healthy diet and we often rely on pre-packaged convenience foods, supplements and processed items or to go the other way and cut out valuable food groups such as carbohydrates, fats and rely on eating ‘superfoods’.
In this guide, we will share what a normal healthy diet is and what your body requires to be healthy. We are all unique individuals whose bodies will respond to different things but the main groups of foods are universal.
Food is more than fuel – our bodies require more than just energy to survive, we require a whole range of nutrients. Macronutrients are required by our bodies in large quantities and supply us with energy, often measured in Kilocalories (kcal) or Kilojoules. Whilst our bodies require micronutrients in smaller quantities, they are just as essential. Macronutrient deficiency can lead to weight loss and starvation whereas micronutrient deficiency can lead to serious health problems.
Protein – Energy density: 4kcal/g (units of energy)
Proteins are known as the building blocks of life. After water, your body is made up of mainly protein. It is used to build and repair tissue such as bone and muscle and support digestion and functioning of a healthy immune system. Proteins also contribute to regulating hormonal processes (which direct your body processes) and building enzymes (which assist your body functions).
Proteins are made up of amino acids – there are 22 amino acids required for the human body. Out of these, 9 are essential as the body cannot synthesise or make these. Proteins from animal sources contain all of the essential amino acids whereas plant proteins are often missing some of these. This means that it is incredibly important for vegetarians and vegans to combine different sources of protein to ensure that they eat all the essential amino acids.
Few foods contain only one source of macronutrient – most of our sources of protein also provide us with fat (animal protein) or carbohydrates (vegetable protein).
Carbohydrate – Energy density: 4kcal/g
Carbohydrates are the body’s primary energy source – particularly for our brain, which can only use glucose (which the body makes from carbohydrates). Eating carbohydrates causes our body to release insulin, turning our body towards burning carbohydrates, and decreasing the amount of fat and muscle we burn. There are two types of carbohydrates: simple and complex.
Fat – Energy density: 9kcal/g
Fat is incredibly important for the human body – without it the body could not
function properly. Fat is necessary for tissue growth and repair, to maintain healthy cell membranes, to regulate temperature and neuron function and production of hormones.
Fat is a concentrated energy source and can contain the vitamins A, D, E and K, which are fat soluble vitamins.
Whilst each individual is unique in their requirements, there are guidelines for what we should eat:
Healthy proteins – include a lean protein source in each meal. Dietary reference intakes suggest 0.8g -1g per kg of body weight a day is enough – for example, for an 70kg person… that is 70 g and the same as eating 275g of raw chicken, cooked. Lean sources of protein include egg whites, chicken, turkey, white fish for omnivores. Vegetarians can try tofu, tempeh, quinoa, lentils and beans as well as eggs.
Eggs are an inexpensive source of high quality protein and hugely versatile. In addition to protein, they are a good source of essential vitamins and minerals. One large egg contains approximately 70kcal and 6 or 7g of protein. Whilst egg yolks are relatively high in cholesterol, egg whites are low in fat and contain all the essential amino acids.
Protein is satiating so eating a small amount of protein in each meal will help you keep fuller for longer. If you are trying to put on muscle or lose fat, a higher protein diet (up to 2g per kg body weight) may help as it will decrease the overall amount of calories eaten. A healthy amount of protein would be a portion the size of the palm of your hand.
Fruits and vegetables – whilst UK dietary advice is to eat 5 portions of fruit and vegetables a day, the latest research indicates that we should eat 5 to 9 portions of at least 80g (what does 80g look like) of each fruit and vegetable a day.
Whole-grain carbohydrates – optimal brain function requires carbohydrates! Whole grain choices are better as they will release blood sugar a little more slowly?. Try quinoa, oats, barley, brown rice, whole wheat bread and starchy vegetables. Whole grains will also ensure that you get enough fibre. The number and size of portions that you require depend on your health and fitness goals and how active you are.
Healthy fats – Our brains and immune systems require healthy fats such as olive oil, nuts, oily fish, avocadoes, nuts. Try to include 2 -3 portions of healthy fats a day – this might include 150g salmon, 2 tbsp olive oil, a handful of nuts
Water – we all need to drink water – at least 2 litres a day, more if you are exercising or going through treatment. Hydration affects our metabolism and brain function. Even being dehydrated by 2% can affect your brain function by 10%.
1. Weigle DS, et al. 2005. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr. 82:41-48.
2. Evans WJ. 2004. Protein Nutrition, Exercise and Aging. J Am Coll Nutr. 23(6)601S-609S.