3 Coffee Habits That Are Silently Wrecking Your Health

0:00 There is one thing that around 2 billion people do every single morning without even questioning it. They wake up and the first thing they reach for before food or before water or before anything else is coffee. And I completely understand why. I drink coffee every single day. It makes you feel a bit sharper. It makes you feel more awake, more alert, more human. But the way the majority of us actually drink it is actively working against us. Not because coffee is bad. The evidence on that is actually really reassuring. I'll come on to that in a few more minutes. But because of the timing of coffee, the additions to the coffee, and the order in which we actually consume it. And those details are quietly setting off a chain of hormonal and metabolic events that explain why by 11:00 in the morning you feel like you need another coffee.

0:53 So, in this video we're going to go through the physiology of what coffee actually does to your blood sugar. Why your morning routine might be creating the crash that you're trying to escape. What the evidence actually says about the best time to drink it. And which milk and sweetener choices are quietly undermining your glucose stability. So, let's start with what coffee actually does in your body because this is quite a complex topic here. Caffeine works primarily by blocking adenosine receptors in the brain. So, adenosine is a chemical that builds up the longer that you've been awake and makes you feel progressively more sleepy throughout the day. Now, caffeine doesn't remove that sleepiness. It just sort of masks it and blocks it. It sits in the receptor and stops adenosine binding to it. Which is why when caffeine gradually wears off and those receptors open back up, the accumulated adenosine then floods back in and makes you feel worse than before. That is your afternoon slump or afternoon energy dip.

1:57 That is the roller coaster that a lot of us feel. But, caffeine also triggers your adrenal glands to release cortisol and adrenaline, your stress response hormones. So, they evolved to give you this burst of energy when you needed to run away from something or fight, like a bear or a lion or a saber-tooth tiger or something like that. And one of the things they do is signal the liver to release glucose into the bloodstream, essentially creating this big energy surge. So, even black coffee with zero calories and zero carbs can produce quite a significant rise in blood sugar in some people.

2:35 Now, a 2021 study in the British Journal of Nutrition found that drinking strong black coffee first thing in the morning before anything else impaired glucose metabolism across the entire morning in healthy adults. People who drank coffee before eating had higher blood sugar after their subsequent breakfast compared to those who had nothing or even just a glass of water first. The effect was particularly pronounced when sleep had been quite poor the night before because bad sleep already elevates your cortisol independently, and then the coffee just sort of stacks on top of that. Which leads directly onto something that the research around continuous glucose monitors has made increasingly clear over the last decade or so.

3:21 And it comes down to the order in which you do things in the morning. Your cortisol is naturally highest in the first hour after waking. This is normal, and it happens in most of us. This is called the cortisol awakening response, and it is completely normal physiology. It is your body preparing you for the demands of the day. But, the problem is that caffeine amplifies that cortisol response. So, drinking coffee immediately after waking pushes your cortisol even higher than it would naturally go, which primes your liver to release glucose, which means when you then eat your breakfast 30 or 60 minutes later, your body is already dealing with elevated blood sugar before the meal has even begun. The spike from your food is therefore higher, the insulin response is larger, and the subsequent crash is more pronounced. If you eat first before your coffee then that picture changes completely. When you eat before your coffee, particularly a breakfast that is high in fiber and healthy fats and protein, your blood sugar rises more gradually. The glucose from your food is absorbed more slowly, insulin is released in a more controlled fashion, and then when you have your coffee after the meal, the cortisol response happens on top of a system that is already in a very stable, fed state rather than a fasted hormonally sensitized one.

4:52 Research from the University of Bath specifically examined this sequence and found really big differences in glucose handling depending on whether coffee came before or after food. So, if you want steady energy throughout your morning, then eat your breakfast first and drink your coffee after. Now, assuming the timing is right, what you actually put into your coffee matters just as much, and this is where a lot of people make choices that seem quite reasonable but are repeatedly spiking their glucose throughout the entire day.

5:26 So, sugar is the obvious one. A teaspoon in each coffee doesn't really sound like much, but if you're having three or four coffees a day, that glucose load adds up really quickly, and each one causes a discrete spike and a subsequent insulin response. The more spikes you have across a day, the more your energy oscillates, and if you want the sweetness, then the evidence supports stevia and monk fruit as the safest options. Both are derived from plants, neither of them really raises your blood glucose, and neither of them appears to carry the negative gut microbiome effects that some artificial sweeteners like sucralose have been associated with. Once you've sorted the question around sweetness, the next question is all about milk, and this is where food marketing has created a significant amount of confusion.

6:16 So, plant-based milks have been positioned as the healthier, more sophisticated choice these days. And for some purposes, they absolutely are, but not all of them behave the same way. Now, oat milk is the obvious one to address here because it's just so popular these days. It froths really well, it tastes pretty good, it markets really, really well as well. But oats are a starch, they are a carbohydrate. And when you process them into milk form, you produce a liquid with a really significant carbohydrate load and a high glycemic response. The processing itself breaks down the fiber that would normally slow glucose absorption in whole oats. So, a 200 mil serving of oat milk typically contains around 15 to 17 g of carbohydrate. Rice milk sits even higher. It's been measured with a glycemic index comparable to glucose itself. It's massive.

7:13 Now, compare that to whole cow's milk at around 10 g of carbohydrate per 200 mil, which also comes packaged with protein and fat that further slows down the sugar absorption and blunts the insulin response. So, if you're having two or three oat milk coffees a day, then you're having two or three glucose spikes that you may not have attributed to anything in particular. You're not eating anything sugary, but your blood sugar is responding as though you have.

7:42 The better choices in terms of glucose impact are unsweetened almond milk or macadamia milk if you can get it, or cow's milk. These are really good for you. Almond milk is pretty low in carbohydrates. Its primary macronutrient is actually fat, and it won't move your blood sugar in any meaningful way. Whole cow's milk, despite its carbohydrate content, has the most long-term evidence behind it metabolically, largely because the fat and protein matrix slows digestion and the natural milk sugars behave very differently to the rapidly absorbed glucose in oats or rice milk.

8:19 Now, if you are going to use plant-based milk, one thing that's really worth doing, regardless of which one you choose, is to actually read the label. Many commercial barista edition oat milks contain added sugar, and the versions used in coffee shops very frequently have sweetened syrups added as a default. So, what you buy in a carton from a supermarket and what goes into your flat white at the coffee shop can be very different things. Now, having said all of that, I want to be really clear about what the long-term data on coffee actually shows because it's really easy to come away from a conversation like this and think that coffee is a problem, but it's not.

8:55 Coffee is actually pretty good for you. So, large prospective cohort studies, including data from the EPIC study in Europe, involving hundreds and hundreds of thousands of people, have found consistent associations between moderate coffee consumption, so around two to four cups per day, and reduced risk of type 2 diabetes, Parkinson's disease, certain liver conditions, and all-cause mortality. And the reason it's so important is that the bioactive compounds in coffee, including chlorogenic acids and polyphenols, have genuine anti-inflammatory and glucose-regulating properties that are independent of the caffeine.

9:35 And the question I get asked all the time around coffee is where is the line with milk? Because a splash in your coffee is very different to a large cappuccino, but where is the line of what's good and what's bad? So, from what I can gather, a splash of whole cow's milk somewhere in the region of a tablespoon or a couple of tablespoons adds roughly 1 to 2 g of carbohydrate and a small amount of fat and protein.

10:03 And obviously, that is not going to really sort of meaningfully affect your blood glucose response in most people, and the evidence supports this. Studies using continuous glucose monitors in healthy adults have consistently shown that small amounts of dairy milk, not the chocolate, but cow's milk, added to coffee does not produce a significant or prolonged glucose spike. But a large cappuccino is an entirely different meal altogether. A standard cappuccino from Costa or Starbucks or wherever, made with around 150 or 200 mil of milk, delivers somewhere between 7 and 9 g of carbohydrate. And if you're having that before breakfast on a fasted system, you are giving your pancreas a real job to do. The milk itself is the meal at that point. That is your breakfast. And the combination of caffeine driven cortisol and an incoming lactose load in a fasted state is exactly the scenario that we've been talking about here. So, for me, the practical line, based on the available evidence, is roughly this. A small amount of milk up to around 50 mil of semi-skimmed or whole cow's milk or an unsweetened almond milk in a coffee consumed after food is unlikely to cause any meaningful disruption to your glucose. But a large milky coffee drunk before breakfast repeated two or three times throughout the day with very little activity is a very different habit with a different metabolic consequence. The issue isn't having a coffee itself, but drinking it on an empty stomach after a bad night's sleep with oat milk or two sugars puts you on a glucose roller coaster that you spend the rest of the day trying to recover from. And even though this might not sound like much to some people, and you know, some of you may be thinking this is all a bit intense. This is just a cappuccino you know, in the morning. I get that, but if you repeat that habit across hundreds or thousands of mornings over decades, then it could have consequences that you may never think of. And in terms of energy, your first drink and your first meal of the day sets the hormonal and metabolic tone for everything else that follows. So, if you get those right, then the energy that you feel at 2:00 or 3:00 in the afternoon without reaching for another coffee will tell you everything you need to know. For me, the bottom line is this. A tiny adjustment to when you drink your coffee and what you put in it is not a dramatic lifestyle overhaul. It is not something you need to obsess over or think about constantly, but if you do it repeatedly every morning across years and decades, it compounds in the same way that any small repeated stress compounds. If you had a tiny misalignment in your car steering, you know, barely noticeable day-to-day, and you drove it like that for 20 years, the wear on the tires and the suspension and the chassis would be significant. Not because any single journey damaged it, but because the same small force applied a thousands of times in the same direction eventually leaves a mark. The biology on blood sugar works the same way. So, two or three unnecessary glucose spikes every day for for years is a meaningful cumulative load on your insulin response, on your metabolic health, and your cardiovascular system as well. This is what the physiology and the science tells us. And the flip side of that is equally true as well. So, getting it right doesn't just mean you feel sharper and more energized to in the afternoon without reaching for another coffee, it means you are actively reducing that cumulative load morning by morning across the decades that actually determines your long-term health. It's just one small habit done very slightly differently every morning.

14:01 And in decades time, your body will notice a difference.