Is a plant based diet healthier than a mixed food diet?

There are growing concerns about both our health and our environmental impact. More people are concerned or are thinking about moving to a more plant based diet. But is it better for your health? Why is plant based food actually important for your diet?


Plant based food are your body’s main source of carbohydrate, your brain’s preferred source of fuel and energy.  Carbohydrates have a direct effect on the release of insulin in the body. Most carbohydrates are derived from real, whole fruits and vegetables. They are released slowly. Causing a steady and prolonged release of carbohydrate and insulin in the body. This is unlike refined carbohydrates such as bread and sugars. Carbohydrates are essential to your body for the building of muscle mass. This helps make you stronger and is also important for managing your weight.

Muscle mass has the most direct effect that you can control on your basal metabolic rate and your total energy expenditure. The reason is two-fold, carbohydrate are used together with protein to enter your cells to build muscle (protein doesn’t enter your cells alone, it does it through a gate that requires the 2 elements). This releases insulin with carbohydrates that are required for the process of building muscle. In addition, carbohydrates are the preferred source of fuel for your brain. If carbohydrates are not present, your brain relies on ketones for energy which is not as good. It can make you drowsy and causes a slight acidity to your blood. Your body has to then later correct this by blowing off the acid from your lungs (which can give you bad breath).


Our main source of fibre is also derived from Plant based food. There are two types of fibre, with very different roles. Soluble fibre, contained in fruits such as raspberries, kiwi fruit and oats are important for managing our blood lipid (fat) content. Soluble fibre “grabs” onto cholesterol and pulls it out of your blood stream, improving your blood lipids. Insoluble fibre, such as in celery improves your bowel health. Insoluble fibre act as both the main source of fuel for your bowel and improves movement through your bowels. This makes you regular and reduces your risk of bowel cancer.

Finally, Plant based food are our main source of other nutrients such as vitamin C, folate (important for health cell replication, especially during pregnancy) and B-carotene for healthly eyes and potassium for normal heart function.

When should I eat different types of Plant based foods?

The choice of high-energy (High Glycaemic Index/Load) or low-energy (Low Glycemic Index/Load) have the biggest effect on metabolism and both are important, if selected at the right time.

Low Energy Carbohydrates, should be consumed at every meal. They slow the release of energy over time during the day. More specifically, the amount would be:

  • 1-2 Cups per meal
  • This includes food such as green leafy vegetables such as spinach and Bok choy, carrots, eggplant, Broccoli and legumes
  • If in doubt about selection, unprocessed and the more colours the better

High Energy Carbohydrates, should be consumed within the first 3 hours after “intense” exercise. This could be heavy weights training or high intensity interval training, not after a gentle stroll. The purpose of this is to replenish your body’s natural short term energy stores (glycogen). This will aid the process of building muscle.  After exercise, the volume should be:

  • 1 Cup of high energy carbohydrate together with 1 cup of low-energy carbohydrates
  • This includes grains, pasta and bananas


The biggest challenge with a plant based diet is meeting your protein needs for 2 main reasons. Firstly, no plant based food has a complete profile of all the essential amino acids (building blocks of protein) that you require. So, the combination of foods that you eat is very important. The protein content of plant food is much lower than meats, so you have to eat much more.

The problem is that grain based food lack lysine. Lysine is an essential amino acid, meaning that your body can not make it from other amino acids and it must be consumed. Legumes are low in methionine (another essential amino acid).  In addition, all plant proteins are also low in leucine and tryptophan. Your body is constantly breaking down and re-making new proteins. This occurs not only in muscle but in all the major processes in the body.  All proteins require all the essential amino acids to be constructed. However, if an amino acid is not present in the process, it will not substitute it with another. It will instead just stop the process and then breakdown your muscle mass (your body’s natural reserve of protein) to get what it needs. This makes it very hard to build muscle mass to manage your weight.

How to meet your protein needs

So how do you do it? The answer is that it is very important to eat a combination of different types of plant based food throughout your day. This means you have to eat legumes AND grain based foods during the day (not necessarily at the same meal). It is easier to eat adequate protein if you maintain a lacto-ovo-vegetarian diet (eat diary and eggs), rather than a strict vegan diet. In general, most vegetarians do meet their recommended daily intake of protein. But, it is significantly lower than that of omnivores or those following a lacto-ovo-vegetarian diet. However, the micronutrient content of these foods is often not enough (most of the major B group vitamins, zinc, iron and calcium). Therefore, if you are to follow a plant based diet, regularly see a dietitian or clinical nutritionist to ensure you are meeting your nutritional needs.

Is a plant based diet healthier?

In general, people following a plant based diet have a lower weight and healthier cholesterol profile than meat eaters. This is due to two things. Firstly its due to their lower energy intake, as plant based food are lower in energy density than meat based foods. Secondly, plant proteins are lower in saturated fats, contain no cholesterol, are higher in fibre and contain more anti-oxidants and phytochemicals. These all help to protect the body. Plant based eaters also generally have lower blood pressure, have a reduced risk of type 2 diabetes and reduced risk of ischemic heart disease. So, a lower risk of chronic diseases.

So, if you are looking to eat a plant based diet for your health and for the environment, there are some real tangible benefits. Particularly for your heart, blood pressure and waist line. But, you need to plan what you eat to meet your full protein and nutrient needs.  Please consultant a qualified dietitian or clinical nutritionist to hold your hand through the process to make sure you do this in a healthy way.

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