Stress Tested

How The New Science of Stress Hormones Can Transform Your Health

By: Dr Richard Mackenzie, Peter Walker

Why do we feel stress? And how can we change things?

Stress Tested is a pioneering collaboration between leading researcher Richard Mackenzie and journalist Peter Walker. Investigating the science of stress hormones, real-life case studies, the history of stress, societal factors and how they interact with stress, Mackenzie and Walker explain exactly how stress works, and what we can do to mitigate its long-term health impact. This is the book exploring the nuances of stress and how it affects you.

You’ll learn how stress impacts and interacts with:

• Your hormones
• Weight
• Type 2 diabetes
• Your work and socio-economic status
• Fertility and pregnancy
• Early childhood and upbringing
• Plus some strategies for coping with stress

It is packed with conversation-starting science and stories. Did you know that low-carb diets can increase cortisol levels, as can HIIT exercise, causing insulin and glucose surges? The opposite of what we have been told in recent times. Or how stress hormones can affect fertility for all genders? Mackenzie and Walker dive into society and stress, considering if the higher rate of type two diabetes in disadvantaged communities is entirely due to lack of healthy food and exercise – or is the stress of poverty itself a major factor?

One thing is clear: stress is complex and personal, with many contributing factors. In Stress Tested, the authors present the view that much (if not most) stress is caused by factors outside of your control. It’s not your fault if you’re stressed. But having the knowledge and understanding of what is happening in your body when stress occurs is a powerful step towards minimizing it.

©2025 Dr Richard Mackenzie, Peter Walker (P)2025 Macmillan Publishers International Limited