Why does seasonal affective disorder (SAD) make us crave carbs?

As the days grow darker and winter arrives, around 3 in 100 of us in the UK experience significant 'winter depression' also known as seasonal affective disorder (SAD). SAD is a type of depression that is influenced by the time of year, and for most people it is triggered by winter.

Wintertime SAD-ness

Even if you enjoy wintertime, at some point or another you will probably have felt a bit down on the more gloomy winter days. This does not necessarily mean that you have experienced SAD, but the effects of reduced daylight hours affect us all internally. For those who are more vulnerable to SAD, these have a more significant effect on their mental health.

Fewer daylight hours trigger a change in our hormones. Melatonin increases, making us feel sleepy, while serotonin decreases, lowering our mood and increasing our appetite. The reduction in natural light also disrupts our internal body clock, ie our sleeping pattern (also known as the circadian rhythm). In people with SAD, these changes are felt more keenly and can lead to symptoms of depression.

Why do people with SAD crave carbs?

Lower levels of serotonin can make us crave foods containing carbohydrates, because these foods are really good at boosting both our mood and our energy levels in the short term. For people with SAD, it is perhaps nt surprising that these carb cravings can be stronger. Reema Patel, registered dietitian at Dietitian Fit explains:

"Carbohydrate-containing food has been shown to boost our mood - so it's only natural that if we have SAD, we want something to help improve how we feel! Often, we get that comfort or pleasure from eating foods that contain carbohydrates.

"Studies show that when you eat foods containing carbohydrates, this helps increase serotonin levels - the 'feelgood' neurotransmitter - in our body. As eating carbohydrates helps to trigger more serotonin release, this can then lead to an increase in wanting these foods during the winter months, when we often want a little more comfort. Carbohydrates give us that boost in serotonin as well as energy levels."

When carb cravings become an unhealthy habit

While loading up on carbs provides short-term comfort, this doesn't last for long and often leads to more cravings. Many studies have found that people suffering with SAD are particularly vulnerable to over-loading on carbs to make themselves feel better. These tend to be snack foods that are high in fat, like crisps and pastries. This has been described as a "tendency to use certain foods as though they were drugs".

Unfortunately, over-eating foods which contain carbohydrates can become addictive for those with SAD who feel a physiological need to increase their serotonin and feel happy. This habit is not a viable way to treat and ease the symptoms of SAD in the long term as it doesn't tackle the route of the problem. Instead, studies have shown that the habit usually leads to weight gain and sometimes other health issues related to an unhealthy diet.

How to treat SAD correctly

Instead of relying on the short-lived lift you get from consuming junk food or carbs, it's important to seek help if you believe you have symptoms of SAD and are experiencing really low moods. Explaining how you are feeling to loved ones is a good first step. Your GP will also be able to talk you through the support available.

You can also make lifestyle changes to ease the symptoms of SAD. The main mood-boosting habits include:

• Exercising regularly.

• Aiming for eight hours of sleep every night.

• Making time for relaxation.

• Ensuring you spend time outdoors.

• Connecting with others.

Controlling carb cravings

It's important to take control of your carb cravings and to comfort eat in a healthy way. This is not about imposing a strict diet, but about allowing yourself the comfort of carbs in a way that's sustainable for your health.

"Be sure that you are not restricting yourself from eating carbohydrates too heavily, especially if you are craving them. This is a sign that your body is saying that it needs some carbohydrates, and you probably would feel a lot better without the severe restriction," advises Patel.

"Eating wholesome, tasty and balanced meals can help us stay full and satisfied for longer, which can then reduce overall cravings. Focus on getting in a good amount of fibre with your meals, as well as whole grains and a good source of protein."

Alongside consuming the right foods, making sure that you take your time while eating may also help to reduce your carb cravings. When you comfort eat, you tend to do so quickly and mindlessly. However, according to research including a 2019 study, eating more slowly "appears to be an effective strategy for reducing food intake" because your body receives cues more effectively when you are full.