How weight loss dieting changes your brain
7 changes your brain makes when you diet that make the diet impossible to stick to
Before jumping into another cycle of self blame for failing the diet, it can be helpful to understand what changes are happening in your body and brain that make dieting biologically impossible to stick to. Your body perceives a diet as a famine and draws on its evolutionary processes to stop you from starving.
Learn 7 ways dieting changes your brain and body function and how you can work with your body to feel good around food
Changes that make you burn less calories
If food is not an option, your body will cut back on using energy (aka calories). Here’s what you may notice.
Your brain will receive chemical messages from your body’s cells that there is not much energy available. No matter what weight you currently are, this is a threat to your body and it will send chemical messages back to your body with instructions to slow down and conserve energy.
After the initial dieting high, your body will slow down your metabolism as much as it can, focusing on using calories just to keep you alive rather than thriving. It will also break down your muscles (including from your organs) to use for energy and this further reduces your metabolism (1).
This is why most people will stop losing weight even when still following a strict diet.
Poor focus and motivation
Concentration on work tasks, going for a run or self care activities that are healthy for your body may seem important to you. But to your brain, they are not worth the energy when you are not eating enough. Your brain will save energy for the most important processes to keep you alive rather than improve your wellbeing (2).
This will likely make you feel unmotivated, fatigued and not able to carry out as many healthy behaviours that are good for your body.
The gut-brain connection is so strong that the brain will actually borrow energy from the gut when you are not eating enough. This causes the gut to start working slower which is one of the reasons, along with muscle weakening and increased stress, that diets can cause bloating, constipation and other painful digestive issues. (3)
Poor concentration, a lack of motivation and low mood are all common side effects of dieting.
Changes in your body that make you want to eat more
Your body does not want to function in this semi- starvation state so it will make chemical changes that help you eat more. Here’s what you may notice.
Chemically, when you are dieting, your brain triggers the release of higher amounts of cortisol, your stress hormone. This helps to keep your body more alert and ready to go seek food but it is also means your body never really relaxes. High cortisol is also a known risk factor for heart disease and other chronic illness (4).
Obsessive food thoughts
One of your body’s natural hunger cues is thinking about food so if you are not eating enough food to satisfy your hunger, you're going to be thinking about food a lot of the time. Your brain will prioritise food thoughts, so food may start to feel obsessive and out of control (1).
If food is not regularly available when you are hungry, then you can’t expect your brain to guide you to stop eating at a comfortable level. Your hunger hormones (ghrelin) and fullness hormone (leptin) are not only controlled by what you eat, but also your thoughts about food.(5).
When you are psychologically avoiding food, your hunger hormones are also affected. This, combined with a disconnect from your body’s fullness and satisfaction cues will drive you to eat as much as you possibly can when food is there, especially of the foods that are off-limits.
Disconnect from your body’s fullness cues
Without dieting, your brain uses complex chemical communication from your body to know when and how much is best to eat. But when we focus on food rules instead of our body’s innate hunger and fullness signals, we can forget, or lose trust with, how to eat in a way that feels good (1).
When you go “off a diet” you may be left without attunement to your body’s hunger, fullness, satisfaction and even emotional signals making eating feel uncomfortable and out of control. This can make you feel you need another diet.
But it is possible to learn to reconnect with your body’s signals to guide your eating so food can feel good without a diet.
How to eat without a diet
To eat without a diet, you firstly need to consistently eat enough. This will ensure your body knows it has enough energy to increase your metabolism and to lower your body’s stress response. Then secondly you need to learn how to work with your body by noticing and trusting your body’s signals for hunger, fullness, satisfaction and emotional needs.
The number one reason people fall back into diets is because they panic and feel unsafe without food rules. But when you take the time to learn how to reconnect with your own body to guide you, eating will feel natural, peaceful and your body will be able to find its healthiest weight without worry of another diet.
Intuitive eating is an evidence-based, step by step approach to learn how to eat without a diet. naturally and peacefully. Grab your free e-book here so you can stop dieting and feel good around food.
- Intuitive eating 4th edition, 2020. Evelyn Tribole and Elyse Resch.
- Centre for Clinical Interventions. WA Health. What is Starvation Syndrome PDF.
- Gut, 2015. Giula Enders
- Tomiyama et at. 2010. Low calorie dieting increases cortisol
- Mind over milkshakes: Mindsets, not just nutrients, determine ghrelin response, 2011. Crum and Corbin.
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