Charting the highs and lows of glucose monitoring and what you need to know when fuelling for sport.
The controversial substance on everybody’s lips? Glucose. Carbohydrates have long been subjected to a witch-hunt by a society looking for solutions to its major health threats; only this time, we’re waging war on blood sugar. The plan of attack? Monitor and flatten the glucose spikes caused by dunkin' donuts, the (previously wholesome) glass of OJ, and even, I’m sorry to say, your Gail’s sourdough.
The UK’s population edges close to 70 million, with one in four adults in the England considered obese, three in four adults aged between 45 and 74 considered overweight or obese, and 7 million people in the UK considered pre-diabetic. So is controlling blood sugar the silver bullet needed to improve the quality of our lives and mitigate the adverse economic impact this substance is said to have on society? Are glucose spikes really the enemy?
It used to be fat
There was a time before carbs were to blame (BC, if you will). Until 2009, the problem was fat. The sugar alarm had already been sounded in 1972 by a British professor of nutrition, John Yudkin, who wrote a book called ‘Pure, White, Deadly’. But Yudkin was largely ignored, and it wasn’t until 2009, when Robert Lustig, a paediatric endocrinologist at the University of California, gave a 90-minute talk entitled ‘Sugar: The Bitter Truth’ that the message hit the mainstream and people took note.
In the meantime, in response to an increase in heart disease, the US government had issued its first Dietary Guidelines in 1980 (the UK followed suit in 1983) recommending that we cut back on fat. As a result, food manufacturers started marketing low-fat products laced with sugar (the most palatable and versatile carb) and consumers started swapping fats for carbs. Ian Leslie writes: “At best, we can conclude that the official guidelines did not achieve their objective; at worst, they led to a decades-long health catastrophe.”
How did sugar become public enemy number one?
Since then, fats have largely been let off the hook. After 30 years of “fat” shaming, the mainstream case began to be built against sugar as public enemy number one.
Lustig’s talk in 2009 ushered in a wave of literature on the topic between 2010 and 2016, as public awareness of the problems posed by an increasingly overweight population began to grow. This was also the time when Deliciously Ella and “clean eating” mantras started to take root. But it’s hard to establish exactly when, and by what, our current obsession with carbohydrates, sugars and glucose was ignited.
Glucose has been getting a lot of attention recently: Steven Bartlett recently interviewed Jessie Inchauspé, better known as the Glucose Goddess, in his Diary of a CEO podcast, which garnered over 4.3M views on YouTube. And then there’s the new wearable that made it onto the front covers of Women’s Health and Men’s Health, Lingo, as well as the now infamous Zoe App.
Here we interview two experts, Renee McGregor (RM) and David Lipman (DL), and share what you need to know to help break this subject into digestible chunks.
Can you tell us a bit more about your credentials and experience understanding glucose?
RM: “I am a sports Dietitian but prior to this I worked in the NHS for the first 10 years of my career working across many clinical specialisms. Understanding how the human body works is a big part of my role as well as providing appropriate advice to individuals and athletes, to support optimal health and performance.”
DL: “I hold degrees in exercise physiology, podiatry and medicine. I also hold coaching qualifications in weightlifting and track & field coaching. I previously worked (for ~3 years) for Supersapiens, the first continuous glucose monitoring company for athletes. I was their Director of Applied Science & Content, wherein I was involved with working with athletes, producing content (blogs, podcast and in-app) to help educate and explain glucose to users and the public. I have also been one of the authors on some of the papers in the industry in continuous glucose monitoring (CGM) use in people without diabetes. Additionally I have worn a CGM for 3 years+ including in ultramarathons and marathons.”
Why is glucose important and what role does it play in the body from a health and fitness perspective?
RM: “In individuals without Type 1 Diabetes, the body has the ability to regulate blood glucose within normal limits by the hormone’s glucagon and insulin. When we consume carbohydrates we break this down into glucose and this is then stored in our muscles, liver, and brain in the form of glycogen until the body needs it as an energy source. When glucose levels drop, glucagon will release glucose, and when glucose levels rise, insulin will be released by the pancreas and lower glucose levels by directing this glucose into storage within the body. It is important to appreciate that the body’s preferred currency of energy is glucose. The brain alone needs 120g of glucose a day to function optimally. When glucose levels in the brain remain chronically low, they can start to have a severe impact on cognitive and reflex function. Similarly, when we are physically active, the body will release glucose from our stores and direct it to the working muscles. This becomes increasingly important when we participate in moderate to high intensity movement, such as running. Studies have also demonstrated that taking on easily digestible sources of carbohydrate, such as chocolate milk post training are ideal to allow for optimal recovery and replenishment. In this situation, the chocolate milk causes a glucose spike, which then triggers insulin which is essential to help draw nutrition back into the body.”
It is important to appreciate that the body’s preferred currency of energy is glucose. The brain alone needs 120g of glucose a day to function optimally. When glucose levels in the brain remain chronically low, they can start to have a severe impact on cognitive and reflex function.
What’s a continuous glucose monitor and how new is the technology? It seems like the field has exploded in the last year.
DL: “A continuous glucose monitor is a biosensor that is attached to the body. The current generations often sit on the back of the upper arm or on the belly. They use a filament inserted under the skin, via a small needle, that then sits in the interstitial fluid (the fluid that is around our cells). This technology is not new (though it is evolving rapidly) and is the standard of care for people with diabetes to monitor their glucose levels. We did a podcast episode with one of the pioneers in the space, Dr Howard Zisser, on the full history of glucose monitoring on the Supersapiens podcast.”
Are glucose spikes bad? Is the aim of glucose monitoring to flatten the spikes?
RM: “While the human body likes to keep blood glucose levels within a certain range, this is not an absolute number and hereby becomes the issue with this new craze of CGM. If you believe the hype, you will think that something terrible will happen if your blood glucose is one point off what is deemed “normal”. However, if you look at clinical data, it is clear that it is actually normal for blood glucose levels to fluctuate a lot throughout the day and to date there are no studies to suggest our glucose levels sitting out of range for short periods of time are harmful to health. This only becomes problematic if your blood glucose remains chronically elevated, which may be as a result of insulin resistance. But again, despite the noise, this is not something that tends to affect everyone. It is associated with Type 2 diabetes and is as a result of a sedentary lifestyle and individuals holding more adipose around their middle. It is a condition that can be reversed by improved lifestyle behaviours. In contrast, Type 1 Diabetics have a lifelong condition. Their pancreas doesn’t produce insulin as a result of an autoimmune condition which is usually detectable at a young age and these individuals need to be given insulin extrinsically, and in this situation, monitoring glucose is advantageous.”
If you believe the hype, you will think that something terrible will happen if your blood glucose is one point off what is deemed “normal”. However, if you look at clinical data, it is clear that it is actually normal for blood glucose levels to fluctuate a lot throughout the day and to date there are no studies to suggest our glucose levels sitting out of range for short periods of time are harmful to health.
DL: “The spike is the immediately obvious thing when using a CGM. Broadly they are caused by food, movement and stress. Limiting stress is probably a good thing to try for most people most of the time. Exercising at higher intensities is good and the spikes caused by this are certainly not an issue - anecdotally this sort of exercise actually seems to stabilise glucose in the following hours and days. Eating foods that are high in sugar or overly processed very regularly isn't a great thing for health, this doesn't need a CGM but the power of seeing the response can help some people to improve their diet. They also help with hidden sugars (predominantly in things like sauces and dressings). Eating in a way that means you have fewer glucose spikes can be a healthier way to eat; more vegetables, less processed and more sustained energy. That said, it can also be very unhealthy (nothing but bacon). So we need to not be caught out by Goodhart's law (when a measure becomes a goal, it ceases to be a good measure). When it comes to athletes, CGMs can be helpful in many other ways: many athletes find they help them to fuel more as an overly low and suppressed glucose can be an indicator of underfuelling or overtraining (particularly overnight average glucose). Similarly, understanding how your body responds to different nutrition products can help use these more tactically (what is quicker and slower releasing and when do I need to use these in race).”
The Glucose Goddess was recently featured on Diary of a CEO, which has caused another uproar (Feb saw the launch of her anti-spike supplements) tackling the so-called dreaded glucose spike. Do you think the industry reaction is justified?
RM: “Absolutely. It is clear that she is creating her own narratives to support her own agenda and also profit from the vulnerable. In my professional opinion, it is clear that she also suffers from disordered eating, most likely Orthorexia which compromises her ability to practice responsibly.”
[Glucose Goddess] is creating her own narratives to support her own agenda and also profit from the vulnerable. In my professional opinion, it is clear that she also suffers from disordered eating, most likely Orthorexia which compromises her ability to practice responsibly.
DL: “It should be remembered that shows like Diary of a CEO are funded by sponsors (and are profitable). These shows need as many listeners as possible and the more shocking the claims the more listens they will get. It should also be remembered that for most people, the simple falsehood is often more palatable and understandable than the complex truth. Glucose can be exceedingly complex, the Glucose Goddess has done a great job of oversimplifying things for the masses. I was recently on a panel at a conference talking about this exact subject and the challenge is we really don't know much about glucose as measured by a CGM (distinct from other measures) in people without diabetes. So we have no reference as to what 'normal' is. Because of this, we really don't have any idea of whether or not glucose spikes are an issue, when they are an issue and even if some are that different to others - which is why the academic industry and dietitians are so up in arms with her. For the most part, some of her 'hacks' can be helpful; more walking to help control a spike, eating more vegetables and less processed foods - these are all fairly healthy things and probably a good thing to do. Others may be a little excessive. A few things to be mindful of are that health and even healthy eating, is more than low or stable glucose. Excessive concern and stress about glucose spikes is probably not a good thing, and one needs to consider their personality and history in this regard.”
The challenge is we really don't know much about glucose as measured by a CGM (distinct from other measures) in people without diabetes. So we have no reference as to what 'normal' is. Because of this, we really don't have any idea of whether or not glucose spikes are an issue, when they are an issue and even if some are that different to others - which is why the academic industry and dietitians are so up in arms with [Glucose Goddess].
The Zoe app has also been receiving a lot of criticism lately. What are the pros and cons of using a CGM and paying attention to glucose?
RM: “The issue with the Zoe app is more the design of the process, the conflict of interest related to the studies they quote and the general flaws in methodology. This is both related to the use of CGM but also testing microbiomes. To date, there are no accurate methods of testing microbiomes but more importantly, there has not been a specific profile of bacteria that has been deemed superior for health. In fact the flora in our gut biome differs and is associated with both genetic and lifestyle factors. Similarly, one key thing that is being continually overlooked with regard to all CGM usage is that ITS NOT JUST FOOD THAT CAUSES GLUCOSE FLUCTUATIONS. In fact, we know that stress, illness, menstrual cycle, dehydration, and movement all contribute. Indeed, a number of case studies have shown that even when individuals eat exactly the same food daily for a week, their blood glucose fluctuates significantly. As food is controlled here, it demonstrates how blood glucose is not just as simple as what we eat. In reality, the only real outcome of succumbing to the trend and using a CGM is that it creates anxiety and obsessive behaviours associated with carbohydrate consumption. As stated previously, some individuals may develop an insulin resistance, but this is rarely those of us who are active and follow general healthy guidelines around eating.”
One key thing that is being continually overlooked with regard to all CGM usage is that ITS NOT JUST FOOD THAT CAUSES GLUCOSE FLUCTUATIONS. In fact, we know that stress, illness, menstrual cycle, dehydration, and movement all contribute.
How would you advise people to navigate conflicting opinions and interpretations on scientific studies? Does it come down to credentials when we should choose who to trust? For example: the Glucose Goddess is a biochemist and Tim Spector (Zoe) an epidemiologist – does this matter?
DL: This is going to get more challenging, not less. These two individuals are probably the tip of the iceberg. We will soon have deep fakes of them, not to mention content from 'AI' and similar entities. My approach, is to consider a few things:
1) Who is talking and what is their perspective? From the Glucose Goddess standpoint, she's got a commercial interest in flattening spikes but has also had many people find benefits in her work. Whereas a dietitian, perhaps with a PhD, has seen many patients with disordered eating and has a vested interest in everyone doing research before making any claims. It's not right or wrong as much as understanding why they say what they say. In my context, having worked with many athletes, I found CGMs generally made athletes eat more, not less! But this is probably a commentary on why they chose to try CGM and the propensity for underfuelling in endurance athletes.
2) Where do the conflicting sources agree and disagree? Are they arguing over significant portions of the topic or a small percentage (often the case). If there are areas they agree, these are probably a safe bet to go ahead and listen to. In the points of disagreement, consider whether there is real disagreement or just disagreement for marketing's sake. One of the strongest forms of marketing is an in/out group or an us/them. Often in health this is the 'sick care system' vs 'wellness and thriving' - again, this is not a criticism but to draw attention to these things to help people understand viewpoints and thus a lens to view the information through.
3) What is your appetite for risk and what is your bias? Some people love to be on the cutting edge and hate missing out. These folks should experiment more. Others, whose bias is perhaps a more naturalistic one, should probably lean toward non-intervention until there is more research.
RM: “This has become something that is really difficult to navigate, especially with so many so-called professionals having online platforms but not actually working hands on with people. They have appropriate qualifications, but they have never worked in the specialism so their knowledge is not nuanced and tends to be very theoretical. That is, they know how to regurgitate the studies but not how to apply this knowledge in practice. In a similar way, academics tend to test a particular hypothesis but they don’t consider how that testing procedure may have negative implications to other processes within the body, resulting in negative consequences. It is important to appreciate that the human body is a series of chemical reactions that all interact with each other and need to work in synergy for optimal performance. So, using the example of Zoe and using CGM, while looking at responses to food alone, there has been no consideration for how hormones, hydration status, activity level or stress also impact the response. By suggesting it is the food alone is not only inaccurate, but also irresponsible as it can limit an individual's diet significantly, leading to nutrient deficiencies. My advice is to check who is giving out the information, what do they stand to gain – Tim Spector and Glucose Goddess both profit from the information they provide; but also checking to see their experience of working with people is quite key.”
With a wave of sugar-free products taking over the market, for those fuelling for physical performance, is it so bad to use sugar-based energy gels and drinks?
RM: “Absolutely not, I repeat glucose is the preferred currency of the body and especially the brain. And yes, while it’s best to consume complex carbs that can be broken down into glucose, in certain situations like before and during endurance and high intensity exercise, easily digestible options, that include sugar, are definitely preferable to support performance and recovery.”
DL: “Health and performance aren't always aligned. Sports nutrition products are often more performance focused than health focused. Similarly, performance itself may not be healthy (what is required to run a 2:08 marathon is probably less healthy than training more recreationally). It's worthwhile considering where on the spectrum of focus between health and performance you lie, your “why” for training/running (and in life). This should help navigate conflicts between the two. A few gels here and there are probably not a huge issue. But consistent use of processed, high sugar foods, year round may be an issue for health, if nowhere else than in your mouth. That said, if the alternative is zero exercise, maybe the net effect is still a positive one. I say all this to say that context matters a little and we need to have eyes wide open on making decisions. Sugar, more specifically excessive added sugar, is probably not ideal for our health but if doing this via gels means less drinking, more exercise and more interaction with a community, it's probably a good tradeoff. Sugar free products are fine but they probably don't serve the purpose of sports nutrition, which is generally to provide carbohydrates for higher intensity exercise. A more 'real food' type approach is probably the better alternative than sugar free products. There is some interesting research on things like mashed potatoes vs gels, which is pretty positive and worth investigating. Fruit of course is another alternative.”
Health and performance aren't always aligned. Sports nutrition products are often more performance focused than health focused. Similarly, performance itself may not be healthy (what is required to run a 2:08 marathon is probably less healthy than training more recreationally). It's worthwhile considering where on the spectrum of focus between health and performance you lie, your “why” for training/running (and in life). This should help navigate conflicts between the two [...] Sugar free products are fine but they probably don't serve the purpose of sports nutrition, which is generally to provide carbohydrates for higher intensity exercise.
Too much of a good thing
So, should blood glucose be receiving so much attention? Experts claim not only that our dependence on all things sweet is the cause of our expanding waistlines and growing health complaints, but that if nothing is done about it, an overweight and obese population is set to cost us $3 trillion a year by 2030 and more than $18 trillion a year by 2060. A mind-boggling stat, particularly when malnutrition and food poverty are still prevalent.
No one has yet identified the driving forces of the narrative demonising carbohydrates, sugar and glucose spikes, but history has taught us that scientific studies can be fuelled by political and corporate agendas. As soon as the media and content-creators catch wind of a new story, especially one sure to hook a readership primed to focus on threats to their health, the result can be a recipe for disaster.
Perhaps the best response to the alarm currently being raised about sugar lies in a holistic approach to the basics and the age-old belief that you can indeed have too much of a good thing.
If you'd like bespoke, expert nutritional guidance, please email hello@onetrack.club to learn how we can support your training.
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