The short version
• - After you eat, blood glucose rises and then falls again. In people without diabetes this is normal, and the body is well equipped to handle it.
• - In some people, glucose dips below its starting level two to three hours after a meal. In a study of 1,070 people, bigger dips predicted more hunger and a higher calorie intake over the next 24 hours (Wyatt et al., Nature Metabolism, 2021).
• - The afternoon slump is largely driven by your body clock and happens even if you skip lunch, but a high-carbohydrate lunch makes it worse (Monk, Clinics in Sports Medicine, 2005).
• - Short sleep matters too: it reduces glucose tolerance in healthy people (Spiegel et al., The Lancet, 1999) and shifts appetite towards high-calorie foods (Greer et al., Nature Communications, 2013).
• - Eating vegetables and protein before starch (Shukla et al., Diabetes Care, 2015) and a few minutes of walking after meals (Buffey et al., Sports Medicine, 2022) both lower the rise in glucose after eating.
• UK adults get around 10% of their energy from free sugars, double the recommended maximum, and 96% fall short of 30g of fibre a day (National Diet and Nutrition Survey 2019 to 2023).
• - Managing blood sugar well looks like steady energy and proper hunger at mealtimes, not a flat line on a glucose monitor.
• - Chromium contributes to the maintenance of normal blood glucose levels, zinc contributes to normal carbohydrate metabolism, and magnesium contributes to the reduction of tiredness and fatigue (GB Nutrition and Health Claims Register).
• - Constant thirst, needing to wee more often or ongoing tiredness are worth raising with your GP (NHS). If you take any medication, check with your GP or pharmacist before starting a supplement.
It is 3pm. Lunch was a couple of hours ago, your concentration has drifted, and the biscuit tin, the vending machine or the leftover birthday cake in the office kitchen has started to feel less like a choice and more like a necessity. If that sounds familiar, you are in good company. UK adults get around 10% of their energy from free sugars, twice the recommended maximum of 5%, and fewer than one in five adults meet that recommendation (National Diet and Nutrition Survey 2019 to 2023).
Blood sugar has become the way many people explain these moments, thanks in large part to Jessie Inchauspé, the biochemist known as the Glucose Goddess. Here, the focus is on the problems themselves, and on what the research says actually helps.
So, this piece looks at the problems people most often link to unsteady blood sugar, namely sugar cravings, the afternoon slump and feeling hungry soon after eating, and what the research says about each. We cover what managing your blood sugar well looks like in an ordinary day, where nutrients such as chromium fit, and when it is worth speaking to your GP.
What happens to your blood sugar after you eat?
When you eat carbohydrate, your digestive system breaks it down into glucose, which passes into your bloodstream. Your pancreas releases insulin, a hormone that helps your cells take up that glucose to use for energy or store for later. Blood glucose rises, then returns towards where it started. In someone without diabetes, this rise and fall is the system working as it should.
What varies is the shape of the curve. White toast and jam on their own are digested quickly, so glucose tends to rise faster and higher. The same toast eaten with eggs, or after a plate of vegetables, reaches the bloodstream more gradually, because protein, fat and fibre slow how quickly the stomach empties and how quickly carbohydrate is absorbed.
People also respond differently to the same food. When researchers at the Weizmann Institute of Science tracked blood glucose in 800 people across almost 47,000 meals, responses to identical meals varied widely from one person to the next (Zeevi et al., Cell, 2015). That is one reason generic lists of "good" and "bad" foods only take you so far.
Why do I crave sugar?
Cravings rarely have a single cause. Habit, stress, tiredness, the smell of a bakery and how long it has been since you last ate all play a part. Blood sugar is one strand worth understanding, because it is one you can do something about.
The clearest evidence concerns the dip rather than the spike. In the PREDICT study, researchers from King's College London and the health science company ZOE gave 1,070 people continuous glucose monitors and tracked more than 8,000 standardised breakfasts and over 70,000 everyday meals. In some people, glucose fell below its starting level two to three hours after eating, and the size of that dip predicted how hungry they felt, how soon they ate again and how much energy they consumed over the following 24 hours. The dip was a better predictor of hunger than the height of the original peak (Wyatt et al., Nature Metabolism, 2021).
Two everyday factors make cravings more likely, too:
• Short sleep. After a night without sleep, healthy adults showed a stronger desire for high-calorie foods, alongside changes in the brain regions that weigh up food choices (Greer, Goldstein and Walker, Nature Communications, 2013).
• A breakfast short on protein, or no breakfast at all. In a small randomised study of 20 young women who usually skipped breakfast, eating breakfast reduced food cravings through the morning compared with skipping it, and the higher-protein breakfast tended to produce the bigger reductions (Hoertel, Will and Leidy, Nutrition Journal, 2014).
So if your cravings tend to arrive at the same point every day, look at what you ate three hours earlier and how you slept the night before, before you blame your willpower.
Why do I feel so tired after lunch?
The afternoon slump is real, and it is not all about lunch. Sleep researcher Timothy Monk at the University of Pittsburgh showed that the mid-afternoon dip in alertness happens even when people have eaten no lunch and do not know what time it is, because it is built into the body's daily rhythm. He also noted that a high-carbohydrate lunch makes it worse (Monk, Clinics in Sports Medicine, 2005).
Sleep feeds into this as well. When healthy young men were limited to four hours in bed a night for six nights, their glucose tolerance was lower than when they were fully rested (Spiegel, Leproult and Van Cauter, The Lancet, 1999). A short night can make the same lunch harder for your body to handle the next day.
The practical takeaway: you cannot remove the afternoon dip entirely, but you can avoid deepening it. A lunch built around protein, vegetables and some slower-release carbohydrate, a few minutes on your feet afterwards and a decent night's sleep all work in your favour.
What can unsteady blood sugar feel like?
No checklist can tell you about your blood sugar from symptoms alone, and the feelings people often link to it overlap with stress, poor sleep, dehydration, low iron and plenty else. With that caveat, these are the everyday patterns that tend to prompt the question:
• Strong cravings for something sweet two to three hours after a meal
• Feeling shaky, irritable or "hangry" when a meal is late
• A heavy, foggy slump after a carbohydrate-rich lunch
• Feeling hungry again soon after a breakfast of cereal, toast or a pastry
• Relying on caffeine or something sweet to get through the afternoon
If these sound familiar, the habits below are a sensible place to start. They are low-risk, inexpensive and good for your health in other ways too.
When is it worth speaking to your GP?
Some symptoms deserve a proper check rather than a change of breakfast. The NHS lists needing to wee more than usual (particularly at night), feeling thirsty all the time, feeling very tired, losing weight without trying, cuts or wounds that take longer to heal and blurred vision as possible symptoms of type 2 diabetes (NHS). If any of these apply to you, speak to your GP, who can arrange a simple blood test.
This matters because many people do not know their blood glucose is raised. Diabetes UK estimates that around 6.3 million people in the UK are living with prediabetes, where blood glucose is higher than usual but not in the diabetes range, and that some of them are unaware of it (Diabetes UK, February 2025). Diabetes UK's free Know Your Risk tool is a useful place to start.
What does managing your blood sugar well look like?
Done well, blood sugar management looks less like a diet and more like a rhythm. You feel properly hungry at mealtimes rather than ravenous between them, your energy is reasonably even through the afternoon, and sweet foods are something you enjoy rather than something you need to get through the day. Here is what that tends to involve.
Start the day with protein and fibre. Eggs on wholegrain toast, Greek yoghurt with berries and nuts, or porridge made with milk and topped with seeds will carry you further than a pastry and a glass of juice.
Build your plate, and start with the vegetables. Fill half of it with vegetables or salad, add a portion of protein and include some wholegrain or starchy carbohydrate. Where it is practical, eat the vegetables and protein first: in a small study of people with type 2 diabetes, doing so led to glucose levels around 29% lower at 30 minutes and 37% lower at one hour than eating the same meal carbohydrate-first (Shukla et al., Diabetes Care, 2015).
Aim for 30g of fibre a day. Fibre slows how quickly carbohydrate is absorbed, and most of us are well short: 96% of UK adults do not meet the 30g recommendation (National Diet and Nutrition Survey 2019 to 2023). Beans, lentils, wholegrains, vegetables, fruit with the skin on, nuts and seeds all count.
Keep free sugars as a treat, not a fuel. The UK recommendation for adults is no more than 30g of free sugars a day, roughly seven sugar cubes (Public Health England). Free sugars include honey, syrups and fruit juice as well as sugar added to food and drinks.
Have sweet foods after a meal rather than on their own. Pudding after dinner arrives in your bloodstream alongside the protein, fat and fibre in the rest of the meal. A chocolate bar on an empty stomach at 4pm does not.
Walk for a few minutes after eating. Even two to five minutes of light walking lowers post-meal glucose compared with staying seated (Buffey et al., Sports Medicine, 2022).
Eat at regular times. Long gaps followed by large meals tend to make hunger stronger and choices harder.
Prioritise sleep. Short nights reduce glucose tolerance and make high-calorie foods more appealing the next day (Spiegel et al., The Lancet, 1999; Greer et al., Nature Communications, 2013).
Notice your own patterns. You do not need a glucose monitor to learn what works for you. A quick note of what you ate and how you felt two to three hours later is often enough.
Where do nutrients fit in?
Food comes first, and no supplement replaces the habits above. Alongside a balanced diet, a small number of nutrients have authorised roles in how your body handles glucose and energy, set out on the GB Nutrition and Health Claims Register:
• Chromium contributes to the maintenance of normal blood glucose levels and to normal macronutrient metabolism.
• Zinc contributes to normal carbohydrate metabolism.
• Magnesium contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue.
Chromium is a trace mineral found in meat, whole grains, fruit, vegetables, nuts, spices and brewer's yeast, but the amount in any given food varies widely with soil, water and processing (NIH Office of Dietary Supplements). Scientists have proposed how chromium works alongside insulin, although the exact mechanism has not yet been identified (NIH Office of Dietary Supplements).
That is the thinking behind our Blood Sugar Support Capsules. Each four-capsule daily serving provides 80 µg of chromium as chromium picolinate (200% NRV), 5 mg of zinc as zinc bisglycinate (50% NRV) and 188 mg of magnesium as magnesium bisglycinate (50% NRV), alongside 800 mg of Ceylon cinnamon bark and standardised extracts of green tea, Citrus aurantium, grape seed and grape skin. It is designed to sit alongside the habits in this article, not to replace them, and it is not a treatment for any medical condition.
If you would like to understand the formula in more detail, including how Ceylon cinnamon differs from cassia and how to read extract ratios on a label, our guide to what to look for in a blood sugar supplement covers it ingredient by ingredient.
Can I take a blood sugar supplement alongside medication?
If you have diabetes, take glucose-lowering or GLP-1 medication, take any regular medicine, or are pregnant or breastfeeding, speak to your GP, pharmacist or practitioner before adding a new supplement. The NIH Office of Dietary Supplements lists insulin, metformin and other diabetes medicines, as well as the thyroid medicine levothyroxine, among the medications that may interact with chromium (NIH Office of Dietary Supplements). A food supplement is never a substitute for prescribed treatment.
Common questions
Why do I crave sugar in the afternoon?
Usually a mix of things: your body clock's natural afternoon dip in alertness (Monk, 2005), a lunch that was mainly fast-digesting carbohydrate, a short night's sleep or simply habit. In some people, glucose also dips below its starting level two to three hours after eating, which is linked to stronger hunger (Wyatt et al., 2021).
How can I stop sugar cravings?
Start with breakfast: include protein and fibre rather than relying on cereal, toast or pastries. Eat at regular times, have vegetables and protein before starchy foods, take a short walk after meals, eat sweet foods after a meal rather than on their own, and prioritise sleep. Cravings rarely disappear overnight, but these habits make them less frequent for many people.
What is a sugar crash?
"Sugar crash" is an everyday term for the tired, hungry, unfocused feeling some people get a couple of hours after a sugary snack or meal. It is not a medical diagnosis, but research shows that in some people glucose dips below its starting level two to three hours after eating, and bigger dips are linked to more hunger (Wyatt et al., 2021).
Why am I so tired after lunch?
The mid-afternoon dip in alertness is part of the body's daily rhythm and happens even without lunch, but a high-carbohydrate lunch makes it deeper (Monk, 2005). A balanced lunch, a few minutes of walking afterwards and enough sleep the night before all help. Tiredness that is persistent or unexplained is worth discussing with your GP.
What should I eat for breakfast to avoid an energy crash?
Build breakfast around protein and fibre: eggs on wholegrain toast, Greek yoghurt with berries and nuts, or porridge made with milk and topped with seeds. In a small study of young women who usually skipped breakfast, eating breakfast reduced cravings compared with skipping it, with the higher-protein version tending to work best (Hoertel et al., 2014).
Can a supplement help with blood sugar?
Food, movement and sleep come first. Chromium contributes to the maintenance of normal blood glucose levels and zinc contributes to normal carbohydrate metabolism, so they can play a supporting role alongside a balanced diet. If you take diabetes, GLP-1 or thyroid medication, speak to your GP or pharmacist first.
The bottom line
Sugar cravings and afternoon slumps are common, and blood sugar is part of the explanation, though rarely all of it. The research points to the dip a few hours after eating as a driver of hunger, to the body clock and short sleep as drivers of the afternoon slump, and to a handful of simple habits that change how your body handles a meal: protein and fibre at breakfast, vegetables and protein before starch, a short walk after eating and regular, unhurried meals.
The goal is not a perfectly flat line. It is steady energy, a calmer relationship with food, and a body that handles a slice of birthday cake without drama. Where nutrients play a part, chromium contributes to the maintenance of normal blood glucose levels, and it sits at the heart of our Blood Sugar Support Capsules. If anything in this article sounds like more than everyday ups and downs, talk to your GP.
Food supplements should not be used as a substitute for a varied, balanced diet and healthy lifestyle. If you are pregnant or breastfeeding, taking medication or have a medical condition, consult your healthcare practitioner before use.
