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Nutrition | Phytonutrients

A Closer Look at Metabolism

We’ve all heard terms like having a “high” or “fast” metabolism and when we hear this it’s common to think of a person who stays naturally slim whilst eating as much food as they want, right?!

The real meaning of metabolism is far more complex than that and, in this blog, we’ll take a closer look at the real meaning of ‘metabolism’ and leave you with some simple and enjoyable ways you can start to better support your own metabolism straight away. 

A well-functioning metabolism is of course important for keeping weight (more specifically, body fat) in check, but a well-running metabolism is also vital for maintaining good health and longevity generally.


In biological terms metabolism refers to the chemical processes that occur within a living organism everyday (i.e., humans) to keep it alive. It’s the process of converting the calories (energy) that we eat into energy that can be used by the body.

We need to consume enough calories each day to keep all the organs in our body, such as the heart, lungs, gut, brain, endocrine and immune system, functioning optimally. The more optimal that energy the more energy for our organs to function at their highest level and vice versa – which is why low-calorie diets, more often than not, after a period of time, lead to low energy and a general slowing down of your metabolism.

A healthy metabolism, or high metabolic rate, is linked to more than just having a healthy weight and the ability to burn more fat – it’s also beneficial, if not crucial, for our hormone health, fertility, immune function, lean muscle mass (muscle is an organ!), cognitive health, energy production, healthy aging and so much more!

After around age 35 your metabolism naturally starts to slow down, at a steady rate year after year, this is as a result of the natural decline in muscle mass which also starts around mid 30s. This is known as sarcopenia, which is Latin for ‘lack of flesh’ and is defined as the degenerative loss of skeletal muscle mass, quality and strength, as well as the replacement of muscle fibres with fat and is specifically related to ageing. Another key factor impacting metabolism is “metabolic flexibility”.


Metabolic flexibility is the ability of our cells to respond or adapt to changes in metabolic demand, such as the type of fuel available for cells to use as energy at any given time (e.g., glucose or ketones), as well as the ability to adapt to changes in temperature. The more metabolically flexible we are the better.


Insulin is a hormone made in and released from the pancreas in response to glucose (sugar) being detected in the blood stream. It shuttles glucose from your blood stream into your (body and brain) cells where it is used for energy either straight away or where it can be stored for later use in the form of glycogen. This mechanism is absolutely VITAL for our metabolic health and overall sense of wellbeing and for prevention of type 2 diabetes and other metabolic disorders. When our cells effectively soak up glucose from the blood stream in response to the action of insulin it is referred to as “insulin sensitivity” or your cells being “insulin sensitive” – this is a very good health protective state. 

Insulin “resistance” however is the condition of reduced “sensitivity” of your cells, leading to chronically elevated levels and is a major player in abdominal weight gain, metabolic disorders and pre-diabetes. The problem is not with insulin itself – insulin is a wonderful hormone with lifesaving effects – but with an underlying metabolic dysfunction where the cells have developed a reduced ability to respond to insulin, causing a compensatory increase in insulin production and elevated insulin levels.

Chronically/ongoing high levels of insulin reduces metabolic flexibility, making it harder for the cells to switch from using glucose for energy to using ketones (metabolites of fat).

Abdominal weight gain or “apple-shape” is usually a sign of insulin resistance. Other signs include fatigue, sugar cravings, high cholesterol and skin tags.

Keeping cells insulin ‘sensitive’ is key, not just for keeping mid-section fat in check, but also for preventing disease. Cells that are “sensitive” to the effects of insulin will effectively soak up glucose from the blood stream when requested to by insulin, allowing insulin levels to return to normal.

Some simple and enjoyable nutrition and lifestyle habits can help to keep your cells insulin “sensitive” and keep your metabolism running nice and high, such as:

  • Continuing to build muscle through optimal protein intake and resistance exercise
  • Walking/moving regularly and especially after meals as studies show a 15 minute walk after eating improves glucose uptake into the cells
  • Eating enough calories (energy) from quality protein, good fats & fibre-rich slow releasing carbohydrates, plus plenty of phytonutrients, vitamins, minerals and fibre from colourful vegetables and fruits
  • Cold therapy such as cold showers and cold-water swimming and heat therapy such as sauna also help boost metabolic flexibility

We hope this has been helpful and empowering for you and happy metabolism boosting for the Junius Team!