Whether from biohacking podcasters, flashy social media ads, nutrition gurus, or blinding ring-lit influencers, you’ve probably heard that well-managed blood sugars are the foundation of good health.
No longer seen as just a concern for people with diabetes, managing your blood sugar is now marketed as the key to a flawless diet, boundless energy, and reduced inflammation.
It’s little wonder that online searches for ‘blood sugar’ have jumped more than 30 per cent in the past five years, and the global market for continuous glucose monitors is projected to grow tenfold in the next decade.
However, despite the gargantuan hype, there’s something most doctors want you to know – most of us really don’t need to worry about blood sugars at all. The health influencers have it wrong.
In the words of Dr Nicola Guess, clinical and academic dietitian at the University of Oxford: “These people don’t know what they’re talking about.”
You don't need to fear the rollercoaster
The main thing you’ve probably heard about blood sugars is to beware the ‘peaks and troughs.’ But what does this really mean?
Well, imagine eating a slice of soft, fluffy white bread. As you digest it, your body breaks the carbohydrates down into glucose – this simple sugar then enters your bloodstream.
If you’re metabolically healthy, your body responds by releasing insulin, a hormone that helps shuttle glucose out of your blood and into your cells, where it can be used for energy. As insulin does its job, your blood sugar levels begin to drop.
Because white bread is a refined carbohydrate, it’s quickly broken down into glucose. This can cause a sharp rise in blood sugar, followed by a rapid insulin response to bring it back down.
The result? A relatively high blood sugar peak leading to a low trough.
At first glance, this might sound alarming. Health influencers often claim that riding the so-called blood sugar rollercoaster leads to inflammation, energy crashes, cravings, and, over time, poor metabolic health.
That’s why they advise against foods that cause sharp spikes and dips in blood sugar, such as white bread, pasta, white rice, potatoes, biscuits, cakes, and pastries.
Instead, they recommend sticking to low-glycaemic foods like vegetables, legumes, meat, fish, and healthy fats, which are said to keep blood sugar levels more stable.
And to be fair, this advice is not entirely wrong. It’s true that eating protein, fibre, and fat alongside carbs can flatten your blood sugar response.
Think of that slice of white bread again: slathering it with butter – which is high in fat – would slow down the absorption of glucose, helping to blunt the blood sugar spike.
Swap the bread for wholemeal, and the extra fibre would help steady the rise even more. Add a spread of oily peanut butter, and the fat and protein would help smooth things out even further.
However, you don’t have to meticulously balance the fat, protein, carb and fibre in each bite of food to be healthy. Despite the bad press, most rises and falls in blood sugar are normal – and for most people they’re nothing to worry about.
“Your glucose should increase after a high-carbohydrate meal. That’s a normal physiological response,” explains Sarah Berry, professor of nutritional sciences at King’s College London and chief scientist at nutrition company ZOE.
“Blood sugar is meant to go up and down, and our bodies are really clever and well able to handle it.”
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Peaks and troughs are normal
One of the most persistent – and misleading – myths about blood sugar is that everyday peaks and troughs trigger harmful inflammation in your body.
You may have seen this in TikTok videos with glucose-monitor graphs or read it in captions under avocado toast photos promising ‘anti-inflammatory’ blood sugar hacks.
However, inflammation isn’t always a bad thing.
“Glucose excursions after a meal do cause inflammation, but that’s because inflammation is a normal response to eating,” Guess says.
Every time we eat, she explains, our immune system ramps up slightly to protect the body from potential incoming threats, like bacteria or pathogens.
This mild, short-lived inflammation is not only expected – it’s beneficial in most circumstances.
“It’s only if your blood sugar levels are excessively high, followed by low dips, that there’s a problem,” Berry says. “If that’s repeated over a long period of time, it might increase your risk of chronic disease.”
In other words, a long-term diet high in refined carbs and sugary treats can lead to frequent blood sugar spikes, which, over time, may increase your risk of developing type 2 diabetes and other metabolic conditions.
But for most people, the occasional rise and fall in blood sugar after meals is completely normal – and harmless.
“Blood glucose spikes or dips won’t cause you any harm, in moderation,” assures Berry.
The mystery of the afternoon slump
You’ve probably heard that fluctuating blood sugar levels cause fluctuating energy – with peaks and crashes blamed for mid-afternoon slumps. While there’s some truth to this warning, there’s still plenty researchers don’t completely understand.
Science in this area is still surprisingly new, but several recent studies, including one led by Berry, suggest that some individuals do indeed feel fatigue and anxiety when their blood sugar dips. But blood sugar is likely just one factor behind this tiredness.
Other influences – such as sleep quality, stress levels, and individual differences in biology – may play equal or greater roles.
“There’s a lot we don’t know,” admits Guess. “Knowing how people feel is really hard to study, because we can’t measure it objectively.”
While the exact causes of fatigue or sudden changes in energy remain unclear, a slight drop in blood sugar isn’t typically dangerous – at least not for people without diabetes.
Your afternoon slump isn’t going to kill you, and it’s unlikely to damage your long-term health.
This is because your body doesn’t rely solely on glucose for energy. You don’t run on one type of fuel. If humans were cars, we’d be hybrids: capable of drawing fuel from multiple sources to keep us going.
“Glucose serves as a petrol – it’s a form of energy in the body,” explains Guess. “Our bodies are able to switch between using the fat in our bodies for energy, and then, when we eat, we use the energy from the meal.”
A short-term drop in blood sugar might make you feel a bit off, but it doesn’t mean you’re running on empty. Your body simply shifts gears, tapping into other energy reserves.
You’re not on the verge of collapse – it’s just your system switching to a different fuel source.
You don't need blood sugar hacks
You may have heard about some blood sugar tips, tricks and hacks for avoiding those pesky peaks and troughs (which, again, are usually fine).
Perhaps you’ve heard, for instance, that you should delicately clothe your grapes in cheese, dip apple slices in peanut butter and begin your meals with vegetables, all in the name of tranquil blood sugar responses.
These hacks might be useful for those with prediabetes, diabetes or insulin resistance, because – as we’ve discussed – adding fats, protein and fibre to your carbs can help calm blood sugar responses.
But for most of us, Guess says these tricks are pointless and unnecessary.
Even for people with metabolic problems, she says, adding extra fats to your food might just add unnecessary calories.
“It’s weight gain that primarily causes insulin resistance, prediabetes and type 2 diabetes, and it’s weight loss that improves all those things,” she explains. “All you’re doing, by adding fat to a carbohydrate, is impeding the effectiveness of weight loss.”
Berry adds that the solution to better blood sugars isn’t quick hacks but rather making sure the meals you’re eating are healthy and balanced, with a mix of protein, fat and fibre.
The problem with blood sugar monitors
Some people take their blood-sugar worry to the next level. In recent years, it’s become increasingly popular for non-diabetics to use continuous glucose monitors (CGMs) – medical devices originally designed for people with type 1 diabetes. Worn on the arm, these sensors track blood glucose levels in real time.
Dr David Unwin, a general practitioner who specialises in nutrition, says that CGMs can be a useful tool for people with diabetes, prediabetes or junk food addiction because they are “like having a policeman on your arm”, giving patients immediate feedback on the hidden sugar in their food.
Many CGM providers encourage participants to wear the device for a short period of time, such as two weeks, to find out how their individual blood glucose levels respond to different meals.
But Berry says that wearing a CGM constantly is not “necessary or useful for healthy people.” Guess warns that doing so can cause “profound anxiety or mental health effects” around food.
In extreme cases, this worry can develop into dangerous eating behaviours, such as orthorexia: an eating disorder characterised by an obsession with attaining perfect health.
To be clear, there is not much empirical evidence of CGM use deteriorating into full-blown orthorexia, and Unwin says that none of his patients seem to have developed eating disorders as a result of monitoring their blood sugars.
But any dietary habit can become obsessive, and Guess says that focusing on blood sugars as a measure of your food’s healthiness is a “false flag”.
Berry adds: “Some people might see a higher glucose spike from a banana than from a cookie and then choose to eat a cookie over a banana in future. Obviously, that’s absolute nonsense.”
Similarly, orange juice may cause a significant blood sugar spike, while an artificially sweetened soda might not. Yet orange juice provides vitamin C and other nutrients, whereas the soda contains artificial additives with little to no nutritional value.
Likewise, lard may have little effect on blood sugar, but as a saturated fat, it can negatively impact heart health.
Ultimately, blood glucose is merely “one part of the puzzle”, says Berry, and dietary advice should consider cholesterol, blood pressure, body weight, gut microbiome, and more – not just blood sugar.
According to Guess, factors like high blood pressure and cholesterol are “far more important than glucose” when it comes to major health risks – particularly heart disease.
In comparison, she says, “the effect of food on your blood sugar likely has a negligible impact on your overall health.”
In short, stop wasting your time: fixating on your blood sugars isn’t going to change much. And if it’s dictating your dinner choices, well, you might be missing the point.
“As a nutrition scientist,” says Berry, “I don’t want to take away the most important thing about food. It’s there to be enjoyed!”
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