The coffee-hormone conundrum: can coffee help with fat loss?

Nov 14

We are often advised to drink coffee in moderation. But where exactly does moderation end and excess begin, and is there a safe grey area in between? Scientists have made many conflicting arguments for both the health benefits and detrimental effects of coffee. In spite of a lingering degree of scientific uncertainty, this beloved brew is here to stay, it is part and parcel of the human experience, as proven by the countless java chains and cafés across the globe. Luckily for us coffee aficionados, findings seem more consistent with the idea that coffee deserves to keep its place in our biorhythms, thanks to its rousing and mood lifting effect, as well as its antioxidant and anti-inflammatory properties - albeit with a few caveats. Following are some of the most relevant merits and drawbacks of coffee, in hormonal and metabolic terms, that I was able to glean, and tips on how to make coffee your metabolic ally.

Coffee and our hormones

Let me make clear at the outset that chemical pesticides and herbicides, in coffee just as much as anything else, are dangerous synthetic estrogens, called xenoestrogens, that forcibly preempt our endogenous estrogen receptors and disrupt our hormonal balance. Estrogenic pesticides like glyphosate may cause breast, uterine and prostate cancers, infertility, hypothyroidism, early puberty in girls, demasculinization of male reproductive traits in male infants, and a host of chronic health conditions. One particular class of highly toxic insecticides used on coffee beans, called organophosphates, interferes with the neurohormonal development of children. A link has been repeatedly observed between prenatal exposure to organophosphates and ASD, autism spectrum disorder, psychomotor and mental development delays in children. Hence, buying a reputable, preferably organic product is always a good idea, seeing as coffee consumption is a daily and virtually life-long habit. This unfortunately comes with a few challenges since growers in different parts of the world have different monitoring systems and laws, in terms of toxic chemical use. For reference, I am providing a link, in the source section below, to the BCGlobal site database of all chemicals contained in different commodities both in the US and abroad.
I came across a study published in 2009 that looked at coffee’s intrinsic estrogenic effect (irrespective of pesticides or caffeine content), and concluded that a natural constituent in it called trigonelline, an alkaloid that gives coffee some of its aromatic properties, acts as a phytoestrogen, or a plant compound that behaves in our body as an estrogen. As with other phytoestrogens, no direct causation was established between coffee and the onset of estrogen-dependent cancers such as breast cancer, This was further validated in 2020 by a large prospective study on postmenopausal women - good news for all of us busy women who rely on that cup (or two or three) of joe. However, with respect to consumption of phytoestrogens in postmenopausal women who have already developed an estrogen-dependent tumor, research is still hard at work. Of note is that a protective effect of trigonelline against colon cancer was observed in the same study. Trigonelline is present in higher concentrations in certain types of coffee beans such as the Arabica and Robusta and it is effectively degraded by roasting. In fact, during roasting, trigonelline undergoes a chemical process called demethylation, which yields nicotinic acid, also called niacin and mostly known as Vitamin B3. Niacin is essential for the produciton of energy in the human cells, where it also acts as an antioxidant. It improves blood flow, combats inflammation, improves digestion, boosts brain function and protects skin cells from sun damage. Hence, the darker the roast, the better. I must admit this came to me as a surprise, since I would intuitively associate roasting with more toxic compounds.
Coffee contains polyphenols, plant compounds that exert antioxidant and anti-inflammatory action in the human body. These include: chlorogenic acid, cinnamic acid, ferulic acid and caffeic acid. Some of these polyphenols belong to a class of chemicals called tannins, which are responsible for its bitter, astringent taste. Chlorogenic acid behaves like a tannin, and it has been shown to decrease the body’s ability to metabolize nutrients for energy, primarily proteins, minerals and B vitamins, which are essential for hormones. Regular consumption of coffee must be associated with a healthy, diverse and nutrient-dense diet, in order to not incur malnutrition. Compounding the problem, detoxification of caffeine from the body may interfere with estrogen clearance: since the same enzymes are needed for the safe excretion of both compounds, caffeine may muck up estrogen clearing pathways in the liver, causing estrogen reabsorption. Women taking oral contraceptives or undergoing HRT metabolize caffeine at a slower rate, which makes it advisable for them to limit intake to a maximum of 2 cups per day.
Coffee beans contain magnesium and potassium, and yet excess consumption of coffee depletes both minerals by ramping up diuresis. Hormone production, uptake and excretion are all enzyme-mediated functions, and magnesium is needed in 700 to 800 enzymatic pathways in the body. For instance, in premenopausal women, there is a natural drop in magnesium levels in the premenstrual week that is associated with PMS syndrome (mood disorders, hypoglycemia, fatigue, depression, dizziness, sugar cravings): symptoms could be improved by a moderate amount of coffee and worsened by excessive coffee intake. This is also due to the fact that magnesium regulates the calming action of progesterone on the nervous system. Thyroid hormones need magnesium: calcitonin, the bone remodeling hormone, needs proper amount of serum magnesium [1.8 to 2.2 mg/dl]; the conversion of T4 to T3, the king hormone in the realm of metabolism, is also magnesium-dependent, which is one of the reasons why hypothyroid patients are advised to limit coffee consumption to 2 cups per day. The loss of potassium associated with the surge of adrenaline, when coffee intake is high, leads to hypertension, arrhythmia and fatigue. Potassium is needed to regulate insulin secretion from pancreatic cells, while insulin is needed to usher potassium into cells: drops in potassium levels associated with diuretics trigger hyperinsulinemia that leads to glucose intolerance. Potassium is also needed to regulate the adrenal hormone cortisol, and it is absolutely crucial to muscle building: athletes who routinely consume coffee for increased endurance may want to avoid habitual overconsumption by sticking to 1.5-2 mg of caffeine per kg of body weight (there are roughly 95 mg of caffeine per cup of coffee). Pre-competition may call for higher doses, usually an additional 50%. For people middle-age and up, the need for potassium in muscle synthesis makes it necessary to maintain consumption of coffee within the generally recommended 400 mg per day, though not all in one sitting. Both magnesium and potassium, along with other minerals like iron, calcium and phosphorus, which may also leach out of the body due to the diuretic effect of caffeine, are bone building troopers, hence again the recommendation to menopausal women to limit their coffee intake to a maximum of 2 cups per day, to ward off osteoporosis and osteopenia.
As per research, chronic caffeine intake improves uptake of serotonin, our happy/calm neurotransmitter, and of acetylcholine, the neurohormone that sparks motivation, cognitive functions and arousal. Caffeine increases output of dopamine, our reward hormone, and modulates the use of GABA, a calming amino acid, by inhibiting its release while increasing its receptors, which, along with the rise in norepineprhine, explains the enhanced alertness. This combination of feel-good neurohormone rush elevates mood, reduces perception of fatigue and boosts energy. However, too much coffee has the inverse effect, triggering anxiety, eliciting negative emotional responses and disrupting sleep, all factors that contribute to poor metabolism and wreak havoc on our hormonal health. By the same token, chlorogenic acid in coffee has been resoundingly lauded by scientists for improving cognitive functions, in fact it has been under the lens of research for its potential role in preventing neurogenerative diseases like Alzheimer’s and Parkinson’s. Epidemiological studies show that the neuroprotective effect of chlorogenic acid is associated with moderate intake of both caffeinated and decaf coffee.
Coffee and fat metabolism
In terms of coffee’s role in weight management, coffee’s fat burning properties are entirely contingent upon our diet and lifestyle, in other words they do not absolve us from responsibility. Let me put that all on the line by breaking things down into five points:
a) Caffeine’s effect on the brain fires up the sympathetic nervous system and the HPA axis (hypothalamus-pituitary-adrenal axis), triggering a quick release of two neurohormones called catecholamines, epinephrine and norepinephrine, and our stress hormone cortisol. This biochemical flurry can be a blessing or a curse, depending on how we consciously handle it. The fight-or-flight call to action spearheaded by these three hormones triggers a rise in glucagon, which tells the liver to convert stored glycogen into glucose, make new glucose and dump all of that sugar into the bloodstream; it ramps up production of insulin by the pancreas; it prompts the release of amino acids from muscles and the mobilization of fats into the bloodstream. All of these moving parts are activated to make energy readily available in the perceived state of crisis. The key here is the fate of freed up energy stores: if that energy does not get utilized, the body re-stores it for later use, in the form of fat. The rise in blood sugar causes a flush of insulin, which over time makes the cells insulin resistant, particularly if sugar and carbs are consumed in excess of needs. Things change if that sugar gets burned off immediately by doing what the body has been primed for: using the fuel circulating in the bloodstream to - you guessed it, fight or flight! Remarkably, during high intensity training, cardiovascular exercise and NEAT, non-exercise activity thermogenesis, since energy needs are higher, a hormone called HSL, hormone sensitive lipase, triggers fat oxidation (burning fat as fuel,) so our muscles can cope. In an inactive body, conversely, LPL, lipoprotein lipase, a fat-storing enzyme, hijacks free floating fatty acids and escorts them back into adipose tissues. Additionally, chronic consumption of caffeine in states of adrenal burn-out (chronic stress) causes the body to sacrifice progesterone, converting it to much needed cortisol. If progesterone goes down, estrogen rises, causing mid-section weight gain. In short: both acute and chronic caffeine consumption induce neurophysiological stress, and stress makes all stored energy available, meaning we have a chance to efficiently burn fat. The rest is up to us.
b) As I stated in the previous paragraph, in the long term, high intake of caffeine may cause or worsen insulin resistance (cells do not let insulin in and blood glucose rises to dangerous levels), and the ensuing hyperinsulinemia (too much circulating insulin) stimulates the release of inflammatory cytokines: high insulin = inflammation. Consumption of coffee tends to be higher among individuals suffering from stress-induced adrenal burnout, because it leads to cravings for stimulants and ‘modulators’ such as caffeine, salt, sugar and alcohol. In the context of a high glucose and high processed food diet, stress, coupled with inactivity and heavy, dysregulated consumption of coffee, feeds a vicious cycle of insulin resistance, inflammation, hyperglycemia, obesity, diabetes and heart disease.
c) Caffeine per se triggers insulin resistance, however only in the short term. As I explained in point a), caffeine plugs in the stress response circuitry, which makes energy available for quick burning. Although insulin production is ramped up by catecholamines (adrenaline and noradrenaline), cell receptors for insulin are temporarily blunted, simply because if insulin got into cells, it would block glycogenolysis, gluconeogenesis, the mobilization of fatty acids and HSL, hormone sensitive lipase, all hormones that aid in releasing stored energy. While being in a state of insulin resistance may sound bad, here again it may or may not be a good thing, depending on timing and context. If caffeine is consumed along with high glucose foods, this may drive blood sugar up, and in the long run, as a repetitive behavior, this would be detrimental, particularly if blood sugar control is compromised, as in metabolic syndrome, prediabetes or Type 2 Diabetes. However, if that cup of coffee is consumed when insulin is at its lowest, i.e. in the morning after a lengthy overnight fast, and caffeinated coffee is not ingested along with carb rich-foods, the body finds ways during that insulin resistance state to burn off energy substrates instead of storing them in the cells. People who practice intermittent fasting, for instance, can greatly benefit from this temporary shutdown of nutrient storing, since morning coffee is usually only laced with fats like MCTs. My suggestion is to switch to decaf if you pair your coffee with carbs, unless of course you plan on engaging in a vigorous workout.
d) Aside from boosting alertness and reactivity, which help tackle and carry out tasks, electrophysiological studies have demonstrated that caffeine also positively impacts excitability of motor neurons. In simple terms, this means that caffeine sparks brain-to-muscle signaling: motor neurons in the brain send neurotransmitters to specific muscle fibers, urging them to release the calcium they have in store, causing contractions which in turn ramp up muscle glucose uptake. These effects, together with the increased release of feel good chemicals like serotonin and dopamine, translate into less muscle fatigue and less perceived effort during physical activity: in essence, in moderate amounts, regular caffeinated coffee indirectly supports a consciously active lifestyle.
e) One final note on coffee’s fat burning properties: earlier in this article I mentioned a compound in coffee called chlorogenic acid, which is marketed in supplemental form as green coffee bean extract. Chlorogenic acid is touted as a weight loss enhancing compound because of its ability to inhibit enzymatic carbohydrate breakdown (by alpha-glucosidase) during digestion, thus reducing glucose uptake, as well as for its ability to reduce triglycerides and ramp up fatty acid oxidation during sleep. Studies have shown dark roast coffee to be more effective in boosting weight loss than light roast, in spite of its lower chlorogenic content. This may be due to the higher availability of trigonelline and its methylated form, nicotinic acid, as discussed in point n.2, which have been shown by studies to exert anti-diabetic effects in mice, by increasing blood glucose tolerance.