I sometimes use coffee and caffeine interchangeably because coffee accounts for most of the caffeine intake among most Western people (while tea is more prevalent among Eastern countries). Let’s face it, next to a glass of wine, Americans love their coffee. But in terms of weight gain, coffee is not so simple. Here’s what you need to know about your drink of choice: Some studies even show drinking three or four cups of coffee a day could reduce your risk of developing type 2 diabetes4 by 25 percent compared to consuming no coffee or less than two cups daily. Other research shows that drinking coffee regularly can lower inflammation and free-radical-induced oxidative stress4, two key players in almost every disease, including obesity. Caffeine also has a thermogenic effect, meaning it can stimulate fat burning. Research shows caffeine can help you lose weight and keep it off5, which is why some weight loss supplements contain caffeine. Considering this scientific evidence, you might wonder if caffeine or coffee even has a dark side (no pun intended). While I have nothing against coffee, it’s important to recognize the risks. These therapeutic, drug-dose amounts can tally up quicker than you might imagine. Bigger sizes and different roasts can become even stronger, and if you’re tempted by free refills, you can easily get a gram or more of caffeine in one sitting. This heavy amount of caffeine (and for some people, much less than that amount) can adversely affect blood sugar levels. Of the seven studies in one review, five showed how caffeine can increase blood glucose levels7 and prolong those increases. Elevated blood sugar levels also spike insulin levels. Insulin is an anabolic or storage hormone. One thing this hormone is very good at storing is fat in your midsection. Keeping insulin elevated can make your cells less sensitive to its “signal”; this is called insulin resistance. To lose weight and keep it off, you want your cells to be the complete opposite—insulin sensitive. Therefore, coffee (caffeine) has the potential of making your cells more insulin resistant. One systematic review and meta-analysis looked at seven qualifying studies and concluded that caffeine can reduce insulin sensitivity6 in healthy subjects in the short term, potentially creating high blood sugar. These results often happen in a dose-dependent matter. What this means is drinking seven cups of coffee will have a more dramatic impact on blood sugar and insulin levels than drinking two cups. But for some people, it doesn’t take much: One study among healthy men and women found caffeine disrupted insulin sensitivity in a dose-dependent manner with no male or female preference, but began at very low doses8. In all fairness, while caffeine can impair insulin sensitivity, researchers surmise the polyphenols in tea, coffee, and other beverages might balance out those effects9. Maybe. Truthfully, studies about caffeine’s impact on blood sugar, insulin, and health factors like obesity and diabetes are all over the map. Fast metabolizers, on the other hand, clear caffeine more quickly, meaning they absorb the antioxidants and other good stuff in coffee without the potential problems of caffeine. In short, slow metabolizers may want to stay away from the most potent forms of caffeine—like coffee. Additionally, looking at the short-term effects of how caffeine affects glucose and insulin levels can’t always explain the long-term effects4 of how caffeine (and coffee in particular) can affect your risk for chronic disease. However, short-term disruptions in insulin sensitivity and blood glucose levels, which can lead to weight gain in the form of increased abdominal fat, then deposits a feed-forward mechanism in your abdomen that propels the forces of weight gain, even as blood sugar levels may have normalized with long-term caffeine consumption. In other words, one problem can create another problem that continues to fuel the fires of inflammation and weight gain. I’m not arguing you should forever give up your beloved morning cup of coffee or mid-afternoon tea, which for some patients can become the best part of waking up or a break in their otherwise-hectic day. For myself, I enjoy a cup of tea with its balanced antioxidant polyphenols and L-theanine for calming the nerves. At the same time, I want you to be aware that too much caffeine—and for some people, it doesn’t take much—can raise blood sugar and insulin levels, which can result in weight gain. That’s why cutting out caffeine in the form of coffee is part of any detox program, including my Happy Gut 28-Day Cleanse. In the meantime, let me help you enjoy your cup of joe while balancing its health risks and benefits. A cutting-edge nutrition deep dive taught by 20+ top health & wellness experts
