Did you know that what you eat can have an impact not only on your appetite, but it can affect your mood, your hormones, and even how well you sleep? If you have a heavy reliance on caffeine or sugar to make it through the day, suffer from mood swings, and often have cravings for certain foods, it’s worth finding out more about how your blood sugar levels could be the root of the problem.
We get the expert insight from Danielle Hamilton, a Certified Nutritional Therapy Practitioner (NTP) and Blood Sugar Specialist. Read on to find out more about the Glycemic Index (GI) and how low GI or high GI foods could be affecting you.
What is the Glycemic Index (GI)?
Thanks to popular culture and social media, most people have heard of ‘low GI’ or ‘high GI’ foods. But what does it actually mean? Danielle explains, “The Glycemic Index ranks foods from 0 to 100 according to how much they cause blood sugar to rise after being eaten. A ‘low GI’ food means that the food is low on the Glycemic Index, indicating it will not have a big impact on blood sugar.”
What happens to the body when we eat high or low GI foods?
When we eat foods that are high on the Glycemic Index, we experience rapid spikes in our blood sugar which is inflammatory to the body. The rapid rise in glucose leads the pancreas to pump out a large amount of a hormone called insulin. Insulin's job is to get the sugar out of the blood by escorting it into the cells of the body - glucose can't get into the organs and muscles without the help of insulin.
When we eat High GI foods, the body "over shoots" and will pump out too much insulin, which leads to a rapid decrease in blood glucose levels. When the glucose levels are plummeting and/or if they go too low, we will start to feel a lot of common symptoms such as dizziness, shakiness, anxiety, irritability, cravings for sweets or carbs, brain fog, difficulty concentrating, heart palpitations, headaches, fatigue, or more. This will then cause a person to reach for more high GI foods because their body is sensing an energy crisis and so the cycle begins again.
On the contrary, when we eat low GI foods, there is only a slight rise in blood sugar and a slight elevation of insulin. If these low GI foods are eaten with a good combination of proteins and healthy fats, a person will feel energised and satiated for hours.
Do low GI foods increase satiety?
There have been numerous studies into the way certain foods affect our blood sugar and the perception of how full we feel. Research from 2009 found that “eating a meal with a low GI (glycemic index) increases gut hormone production, which leads to suppression of appetite and a feeling of fullness.”
A large, long-term study set out to explore if low GI foods can help with the increased hungriness felt when trying to maintain weight after a period of weight-loss. What this study found is that a high protein, low GI diet does suppress hunger after weight loss, however it doesn’t necessarily prevent weight regain.
What these studies tell us is that eating foods that are low on the Glycemic Index can be a useful tool if you often feel hungry or have cravings, especially if you are on a weight loss journey. Danielle explains the benefits of low GI foods on satiety. “When our blood sugar is stable, we feel energised and satiated. Low GI foods help to keep the blood sugar in that happy range which will naturally keep your appetite more regulated.”
She goes on to explain that, “It's important to note that not all low GI foods are created equally. We need to look at the macronutrients (carbs, fats and proteins) in each food. Foods containing high amounts of proteins and healthy fats are naturally low GI because fats and proteins don't have a large impact on our blood sugar. These happen to be the most satiating foods. Even if a food is low GI but contains mostly carbohydrates with very little to no fat or protein, it will not be very satiating. Carbohydrates are like kindling whereas fats are like logs on a fire. Carbs burn up hot and fast and leave you hungry very shortly after you finish eating them.”
Do high GI foods make you hungry?
So if low GI foods can help you to feel fuller for longer, do high GI foods have the opposite effect? Dr Sharma, a Professor of Medicine in Berlin, explains the science behind it. “A popular narrative by proponents of low Glycemic Index foods is the notion that high Glycemic Index foods lead to a surge in plasma glucose, which in turn stimulates a spike in insulin levels, resulting in a rapid drop in blood glucose levels and an increase in appetite ('crash and crave).”
A High GI food is considered to be a food with a GI rating of 70 or greater. Breakfast cereal cornflakes is one of the highest GI foods you can eat, with a rating of 86. White bread is also high with a rating of 75, and a boiled potato has a rating of 78.
High GI foods increase your appetite and cravings for several reasons. Firstly, high GI foods spike your blood sugar which leads to a crash. As your blood sugar is crashing down, your body will sense it's running low on energy and will turn on symptoms that make you want to eat more - you may feel cravings, anxiety, headaches, irritability, "hangry", tired, or more.
Another reason High GI foods make you feel hungry is because they're often devoid of protein. Protein is the most satiating macronutrient and when we get enough protein, the body feels it's had enough and will turn off your appetite. However, with high GI foods like potato crisps, crackers, corn, or french fries, these foods are devoid of protein. The body will not get the message that it's satiated, so you can easily overeat these foods. Therefore, ensuring you are eating a good amount of protein at mealtimes can help you stop overeating and also help tame your appetite.
What are the best low GI foods?
So we’ve established that in general, it’s best to stick to low GI foods if you want to balance your blood sugar levels throughout the day and avoid negative symptoms. But what are the best low GI foods?
Danielle explains, “The best low GI foods are those that contain protein, fat, fibre or a combination of the three. Good examples are meat, fish and whole eggs (especially the fattier ones) because they help keep blood sugar stable and keep you full for hours. Fatty fruits like avocados, olives, and coconut are great because they contain fats and fibre with very little sugar or carbs so they also help to keep your blood sugar stable. And finally low GI vegetables that are "non starchy", such as mushrooms, courgette, and other green vegetables which contain lots of fibre to help to slow the absorption of sugar into the bloodstream.”
The effects of a low GI breakfast
Superzeros is a unique cereal in that it contains zero sugar and a high amount of protein - the ideal equation for regulating appetite and preventing sugar crashes. When we eat a high GI breakfast, such as white toast with jam or a traditional sugary cereal, our blood sugar will come crashing down within a few hours which will drive us to seek out more food.
Danielle explains, “Chances are, if our blood sugar is dropping quickly, we will tend to want ‘fast energy’ that usually comes in the form of other high GI foods. This blood sugar rollercoaster tends to repeat over and over all day long.”
On the other hand, if we eat a low GI breakfast like Superzeros, we will feel energised and satiated for hours. This will decrease cravings throughout the day so we can have an easier time eating healthy foods and preventing weight gain.
Regulating appetite with low GI foods
The Glycemic Index is only one tool we have for predicting how a food will impact blood sugar. The presence or absence of other foods really matters too. As mentioned above, classic breakfast foods such as whire bread or cornflakes are among the highest GI foods you can eat.
Combining low GI foods with proteins, fats, and fibres (from non starchy vegetables) can be a great way to further reduce the blood sugar spike from your foods. The best way to know how a food or foods may impact your blood sugar is by testing with a finger stick device or with a Continuous Glucose Monitor. This will help you customise which foods, in which quantities, and at which times work best for your body.
About the author: Alex Parren is a Freelance Health & Fitness writer as well as a qualified Personal Trainer and Nutritionist.