In part 1, part 2, and part 3 of this series of articles, we introduced the 'personal fat threshold' hypothesis, the body's key energy systems regulating both fat and carbohydrate, and how insulin resistance will influence your personal fat threshold.

The key message so far has been that the body's ability to store fat in the form of subcutaneous fat in the adipose tissue is a protective mechanism. It protects the vital organs from having to store fat and therefore, enables them to maintain normal function.

Underlying the functionality of our energy systems and vital organs is insulin. Insulin plays a key role in how efficiently we can store and burn energy. When our body becomes insulin resistant, our ability to regulate energy is significantly reduced, meaning our chances of reaching our personal fat threshold and developing type-2 diabetes increases.

Today's article will focus on the main lifestyle habits and practical tips you can introduce to reduce your insulin resistance, stay within your personal fat threshold, and ensure you're keeping your body's energy systems functioning well.


We discussed in part 2 that the two main factors influencing excess fat storage is our energy intake and our insulin levels. In today's modern environment, processed foods (such as cereals, supermarket bread, cakes, biscuits, crisps etc) are not only energy dense, but they also cause large insulin spikes due to their high content of refined carbohydrates.

Over time, this prevents our body from burning excess fat, which means we may reach our personal fat threshold more quickly because our adipose tissue struggles to continue to grow new fat cells, or expand existing ones.

Following the Second Nature guidelines is a good place to start. The lower-carbohydrate approach, coupled with a focus on fresh whole foods such as vegetables, meat, fish, dairy, nuts, legumes, and whole grains, naturally increases your protein and healthy fat intake. Protein and fat are digested more slowly than carbohydrates, providing a more stable energy release throughout the day. In addition to this, the insulin response to these nutrients is also much lower compared to the insulin response to carbohydrates.

This means your adipose tissue will be 'mobilising' more fat to be used for energy, rather than consistently being forced to store it. It also ensures that you don't 'max out' your glycogen stores, ensuring that when you do consume carbohydrates, your body will have a place to store them for later use.

As we highlighted in part 3, your body wants to be in a constant state of energy use and storage, which we refer to as 'energy flux', rather than simply a constant state of storage (which would occur with a diet high in processed foods). Our nutrition guidelines will encourage your energy systems to be cycling through energy use and storage in a healthy balance.

Key points

  • Processed foods lead to excess fat storage by both increasing circulating insulin levels and contributing to excess energy intake
  • Our body's energy systems want to be in a constant state of energy usage and storage to function correctly, this is known as 'energy flux'
  • The Second Nature guidelines provide a more stable energy release throughout the day and won't cause the same insulin response you'd experience with processed foods
  • Our approach will encourage your body to be in a healthier balance of storing and burning energy


As we've mentioned above, the body's energy systems want to be in a constant state of energy flux. There's no better way to get your energy systems in a state of energy use than exercise!

Below, we've highlighted the key differences between strength and aerobic training, and why it's important to include both in your exercise routine to achieve maximum benefit.

Strength training and high-intensity exercise

Strength and high-intensity training support our body's energy systems in the following ways:

  • Increases the volume of glucose that's moved from the bloodstream into the cells to be used for energy
  • Increases the volume of glucose that's moved into the cells to be stored as glycogen
  • Improves insulin sensitivity, meaning that insulin is able to function more effectively
  • If you increase your muscle mass through training, you can also increase the volume of glycogen that can be stored in your muscles. More muscle = more glycogen capacity = less excess glucose to be stored as fat.
  • Increases the body's ability to burn glucose as a fuel source

Some great options for this type of training are:

  • HIIT
  • CrossFit
  • Circuit training
  • Interval training
  • Weight lifting
  • Resistance bands
  • Bodyweight workouts

Find more inspiration in the Exercise toolbox in the app!

Aerobic training

This type of training has a whole wealth of benefits associated with it, including specific adaptations to your body that improve the function of your energy systems:

  • Increases the volume of fat that is 'mobilised' and burnt for energy
  • Similar to strength training, it increases the volume of glucose that's moved into the cells to be stored as glycogen
  • Improves insulin sensitivity, meaning that insulin is able to function more effectively
  • It increases your cells' ability to burn more energy by increasing the number of mitochondria (where your cells burn energy) in your cells
  • Increases the body's ability to burn fat as a fuel source

Some great options for this type of training are:

  • Jogging
  • Hiking
  • Cycling
  • Swimming
  • Rowing
  • Walking

Find more inspiration in the Exercise toolbox!

When is the best time to exercise?

The best time to exercise is the time in which you're most likely to do it! Consistency is key with exercise. If you enjoy exercising in the evening rather than the morning, then you should continue to exercise in the evening, and vice versa.

Key points

  • Both strength training / high-intensity exercise and aerobic training improve the body's energy systems, but through different pathways
  • Strength training and high-intensity exercise predominantly requires glucose for fuel and improves the body's regulation of glucose to a higher degree than aerobic training
  • Aerobic training improves the body's ability to burn fat, and improves the body's regulation of fat to a higher degree than strength and intensity exercise
  • Both forms of training improve energy regulation and reduce insulin resistance
  • The best time to exercise is the time that you're more likely to continue and make it a habit

Stress and sleep

There are many ways in which a lack of sleep and chronic stress can have a negative impact on our body's energy systems, but one of the primary issues appears to be the increase in the stress hormone cortisol.

Cortisol is released during times of stress to increase the release of glucose into the bloodstream from the liver. This ensures that your body has enough 'fast fuel' available in times of stress, such as pressing the brake in your car if you see an animal on the road, or running away from a threat.

But if you're constantly in a state of sleep deprivation or stress, and your body is constantly releasing high levels of glucose into the bloodstream, then your body will also be releasing higher levels of insulin. This can then lead to the issues described in part 3, with an increase in insulin resistance in the muscle and adipose tissue.

In this context of cortisol-induced insulin resistance, there are some proven ways to reduce your circulating levels of cortisol and reduce stress:

1) Low-intensity exercise

While higher-intensity exercise can be a great tool to use, it actually increases levels of cortisol in your bloodstream in the short-term. This isn't an issue for an individual with normal lower cortisol levels, as they will return to baseline after the exercise.

However, if you're experiencing chronically high levels of cortisol due to stress or lack of sleep, then you might want to avoid adding additional stressors to your lifestyle.

On the other hand, lower-intensity exercise has been shown to reduce cortisol levels. Some great options are:

  • Walking
  • Yoga, pilates, tai-chi
  • Stretching
  • Low-intensity cycling
  • Low-intensity swimming (breastroke)
  • Any exercise you can do at a lower-intensity

Find more inspiration in the Exercise toolbox!

2) Deep breathing exercises and meditation

Deep breathing exercises have been shown to reduce circulating cortisol in the short-term, but the long-term impact of deep breathing as a strategy to reduce stress is unclear. However, mindfulness meditation has been shown to have a positive impact on the structure of the brain's stress management system.

These positive changes allow the body to manage stress better. This means that practicing mindfulness meditation will not only have a positive impact by reducing circulating cortisol in the short-term, but also improving the body's ability to keep cortisol levels down in the long-term.

A great place to start is to practice 2-minutes of deep breathing every day. If mindfulness meditation is something you'd like to develop into a habit, we can recommend the apps, Calm, Headspace, Insight Timer, or Smiling Mind. There's also an introductory video for meditation here.

3) Accessing nature

Observational research has shown that individuals who spend more time in nature (e.g. by visiting local parks or the countryside), have lower levels of self-reported stress. Research has also shown that when people that look at 'fractals' (geometric shapes found in nature, such as leaves) their circulating cortisol levels drop.

This suggests that accessing some form of nature - whether that be a garden, your local park, or your surrounding countryside - can have a positive impact on your cortisol levels, and therefore, your insulin resistance over the long-term.

Some activities we'd recommend adding to your weekly routine could be:

  • Gardening
  • Growing food and herbs
  • Walking or hiking in nature
  • Exercising in nature or your local park
  • Joining a local gardening or walking group


As we mentioned above, stress and a lack of sleep have a similar impact on our body's circulating cortisol levels, which then increases our insulin resistance.

You'll see in the image presented below our top tips for improving your sleep, which can you read about in more detail in our guide here.

Key points

  • Chronic stress and a lack of sleep both increase the stress hormone cortisol, which increases circulating glucose
  • This can lead to increased insulin resistance which has a negative impact on your body's energy systems
  • Being able to lower cortisol, and maintain lower cortisol levels, will help to reduce insulin resistance
  • Low-intensity exercise, deep breathing, and mindfulness meditation are all proven ways to reduce circulating levels of cortisol
  • Improving sleep hygiene can also lower circulating cortisol

Take home message

The personal fat threshold can be described as the 'tipping point' at which your body can no longer store fat in the adipose tissue as subcutaneous fat. It's at this point that more fat will be stored in your vital organs, such as your liver or your pancreas, and chronic diseases such as type-2 diabetes will develop or accelerate.

Your body's energy systems that govern how and where your food energy is stored, are primarily influenced by your lifestyle and your level of insulin resistance.

All areas of your lifestyle can impact your body's ability to regulate food energy. As we discussed today, it's not just about diet and exercise, but also sleep, stress, and relaxation, among other elements we cover in the Second Nature programme. Your body is a very complex biological system!

Hopefully, over the course of this series you've developed a greater understanding of how your body functions, but also the lifestyle strategies that you can implement to improve your health for the long-term.

Article written by Robbie Puddick, Registered Nutritionist and Second Nature Health Coach

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