Mood? Vitality? Why our mental health is all about our energy levels


Our mental health is linked so much to our energy levels. Our blood sugar levels can help regulate our emotions, sleep and resilience to stress. Both under and overeating and eating too little or too much dietary sugar, cause blood sugar levels to fall, making us feel hungry. Our brains see hunger as a stressor that triggers the flight or fight mechanism, and so hunger can cause anxiety and low mood depressive symptoms. Low blood sugar can also be an appetite stimulant. A routine of three regular meals, with a high-fibre breakfast as soon as you get up, and lots of low glycemic index, complex (low simple sugar) carbohydrates, probiotics, prebiotic fibre, lean protein, healthy fats and water, can be essential in regulating blood sugar and helping you keep your emotions, mood and appetite for food and life, stable.

Our blood sugar level is regulated by the hormones Insulin and Glucagon. When we eat carbohydrates or fat our blood sugar rises and glucose receptors in our blood stimulate Insulin production from the Islets of Langerhans in the pancreas. Any surplus energy is stored as a chemical called glycogen in the liver or in adipose (fat) tissue. When our blood sugar gets low Glucagon converts some of these glycogen stores back to glucose and once this energy is used, it triggers the release of Ghrelin, the appetite stimulant hormone, which makes us eat. Once we are full, Leptin, the satiety hormone and Insulin are released and the cycle starts again.

If we eat too little Insulin is permanently high in our blood, this is why diets fail as they make you too hungry. However eating a diet with lots of sweets, chocolates, sugary drinks, doughnuts, cakes, crisps, sugary milk and biscuits, also causes high Insulin levels. This is because these are simple sugars that cause quick-acting but short-lasting energy. They cause a quick surge of energy in the blood and then a massive Insulin peak. Insulin quickly removes these sugars from the blood and so these cause a massive dip in energy levels, making you feel lethargic, tired and hungry, anxious and depressed. Sugary foods actually reduce focus, and concentration and increase appetite. The more sweet treats you eat, the more hungry you feel. If you regularly overeat, you can become Leptin resistant and develop a “bottomless pit” appetite where you do not recognise the appetite signals that tell you when you are full. You can also develop type II diabetes where you are resistant to Insulin.

Why does low blood sugar make us feel stressed and low?

“Hangry” or hungry-angry, is a state that exists when you have low blood sugar. Your brain sees hunger as a stressor and goes into defence mode. When you have low blood sugar your brain is in permanent “flight-or-fight” mode, as it is wanting you to go out and hunt-and-gather food. In this mode, it deprioritises non-essentials like your immune system, digestive system and also your emotions so it can focus on giving your muscles energy so you can go out and find food. This state causes low moods, making you interpret situations in a more negative way and less likely to find cognitive solutions to problems and think creatively. In this state, you are less able to learn, process information, regulate your emotions and are more likely to fly off the handle with little reason.

How can we regulate blood sugar?

1) Regulate Insulin levels.

Insulin is the hormone that regulates blood sugar. When we eat we either convert this glucose from food and drink to energy or convert the glucose in the blood to glycogen (stored in the liver) or fat (adipose tissue). Insulin levels are both conditioned (hence the need for regular mealtimes at the same time each day) and have natural circadian rhythms. Insulin goes up during the morning and then at night time goes down. Insulin levels and cortisol levels peak when we first get up in the morning and so it is best to train your body and get into a routine that balances the Insulin and eat a high-protein and fibre breakfast as soon as you get up. Breakfast is essential for regulating blood sugar. You should eat it even if you are not hungry, as it actually stops hunger and makes you less likely to snack later on in the day. However do not overeat. Have a balanced low-sugar, high-protein and fibre portion of breakfast and stop. Overeating can lead to Insulin resistance (such as in type 2 diabetes)and Leptin resistance where you fail to recognise your own satiety signals and diabetes can be life-threatening.

2. Reduce stress

Hormones released in times of acute stress, such as adrenaline, stop the release of insulin, leading to higher blood glucose levels to help cope with the stressful event. This gives us lots of energy when we are anxious or stressed and then causes energy crashes where we crave quick energy supplies (simple carbohydrates).

3. Reduce the glycaemic index (GI) of what you eat

Low blood sugar does not mean you should eat lots of refined high-glycemic-index sugars. Sugars are carbohydrates, and there are two types of carbohydrates, simple (glucose, sucrose in fruit, fructose, lactose in milk) and complex (starch, cellulose, fibre). Simple sugars provide quick-acting and short-lasting energy, complex sugars provide slow-acting but long-lasting energy. The best way to balance your blood sugar levels and regulate your appetite so you never feel hungry is to consume lots of complex low glycemic index carbs. These are found in high fibre (plant-based), unprocessed carbohydrates such as potatoes, carrots, bran, oats and nuts and seeds. These provide long-lasting energy and prevent the energy slumps that increase appetite and cause decreased mood.

You can also increase the glycaemic index of carbohydrate-rich staples (so you have more energy for longer) by adding fat such as olive oil to white bread or rice, adding high fibre vegetables, using parboiled rice instead of processed white rice, incorporating condiments such as cinnamon, lemon juice, soya sauce, vinegar and ginger into foods (as they have been shown to lower blood glucose levels) and adding protein to your carbohydrates.

4. Eat protein

Chicken for dinner anyone?

Protein is also essential for regulating blood sugar and lowering the glycaemic index of meals. Every meal should contain some protein, whether milk in your cereal (dairy or plant-based milk like soya, pea, almond or oat milk), cheese, meat, tofu, eggs, fish, nuts, seeds, peas, broccoli, beans, sprouts or whatever your preference. Protein is needed for growth and repair and is also a great long-lasting energy source that our bodies use once it has used other sugar sources. Dietary protein is also needed as a supply of amino acids (proteins are made of amino acids) to make some key brain chemicals involved in mood regulation such as tryptophan for making Serotonin (the happiness chemical).

5. Sleep

Sleep and rest are also essential for regulating blood sugar. Our brains interpret a lack of sleep as a stressor. In stressed “flight-or-fight” mode, our brain's Hypothalamus releases Adrenaline hormone into the bloodstream, which prepares the body to escape from a perceived threat. The morning after a night of no sleep, you have a burst of energy, as Adrenaline directs dietary sugar to the muscles. Blood sugar rises, followed by a surge in Insulin hormone, which causes you to eventually crash and feel tired and hungry. A lack of sleep also increases circulating

6. Eat fat

Low-fat products make you fat. Ironic isn't it? Fat is needed to absorb key fat-soluble vitamins and minerals. Our brain is also made of fat. Full-fat Greek yoghurt is also more filling and maintains your energy levels for longer. Fat-free products are also more likely to contain refined sugars, more simple carbs and sweeteners, which cause dips in glucose levels and increase your appetite and lower your mood.

7. Iron and vitamin C

Low iron levels are responsible for so many mental health conditions. Iron is needed in red blood cells to carry the oxygen we need to make energy. It is also needed for immune function, wound healing, reproduction and growth and development. We need vitamin C to absorb iron. You can get vitamin C from many low-GI fruits and vegetables such as strawberries, broccoli, brussel sprouts, peppers and tomatoes. Iron is rich in beans, eggs, green vegetables (such as spinach, kale, broccoli), meat, nuts, peas, soy products, whole grain fortified cereals and breads, seeds and seafood (such as tune, sardines, haddock, shrimp and oysters).

8. Watch your Dopamine

Dopamine is the brain neurotransmitter that is released in response to reward, learning and pleasure. It is also associated with addiction and energy and motivation(as it works with Adrenaline and Serotonin). The more dopamine you have, the more your brain downregulates the dopamine D2 and D3 receptors in your brain. Our phones, exercise, sugar, fat, sunshine and pleasure increase Dopamine. Low dopamine causes depression, which is part of what causes seasonal affective disorder in the winter. To regulate your Dopamine levels, ensure you have occasional “digital dopamine detoxes”, get out in the sun in winter, and do things you enjoy when low, as it will give you energy and motivation. Learning and accomplishing things will also give you energy.

So our mood and appetite are all about energy

Vitality is the state of being active. The more energy you have the more of an appetite you have for life and the more full you feel. Balance your energy levels and you balance your life.

Copyright Laura Campbell


  1. Björck, I., Liljeberg, H. and Östman, E., 2000. Low glycaemic-index foods. British Journal of Nutrition, 83(S1), pp.S149-S155.
  2. Mattei, J., Malik, V., Wedick, N.M., Hu, F.B., Spiegelman, D., Willett, W.C. and Campos, H., 2015. Reducing the global burden of type 2 diabetes by improving the quality of staple foods: The Global Nutrition and Epidemiologic Transition Initiative. Globalization and health, 11(1), pp.1–20.



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Laurentia (Laura)Campbell

Laurentia (Laura)Campbell


Neuroscience, mental health and nutrition academic and writer. Life-experimenter, trying to add value with an insatiable appetite for actioning positive change.