The holidays are upon us. It’s only October but with the rate this year has gotten to the tail-end, we’ll all be wearing our favorite sweaters (forcibly or otherwise) and devouring the holiday away in no time.
The forward-looking you will already be starting to watch that *extra holiday weight* before the holiday even starts.
But one step at a time, right? After all, there’s a few weeks left before the celebrations and holiday parties officially kick in.
If the java lover in you has ever been curious whether caffeine can help curb the appetite, now is the perfect time to find some answers.
The word on the street is that caffeine is one of the best appetite suppressants. But is this really the case?
Spoiler alert: research tell us the jury’s still out on this one.
Is caffeine a natural appetite suppressant? What researchers say
There are research and studies conducted throughout the years that say caffeine may or may not be the best appetite suppressant:
While further studies are needed, one research study  shows that having your caffeine fix half an hour to about 4 hours right before eating may affect your appetite, specifically gastric emptying and the feelings of being hungry.
A moderate amount of coffee can “effectively reduce energy intake in the following meal and in the total day compared to lower or no coffee intake in overweight/obese participants.” 
Caffeine’s impact on appetite may be different between men and women. In this study , subjects were all given either 300 mg of caffeine or a placebo half an hour before a meal. Results show that men experienced a 21.7% dip in calorie intake, while women didn’t experience any change at all.
While no particular study pertains to green tea extracts as an effective appetite suppressant, mixing it up with other ingredients may effectively decrease your longing for food. [4, 5]
Livestrong refers to a 2009 study that shows green tea - with or without capsaicin - could help reduce the appetite and calorie intake. 
In a study published in "Clinical Nutrition" in January 2009, 27 participants consumed capsaicin, which occurs naturally in hot peppers; green tea, which contains caffeine; sweet peppers; capsaicin plus green tea; or a placebo on 10 separate days. Researchers then analyzed the participants' appetite, food intake, body weight, and heart rate and found that green tea consumed with or without capsaicin led to increased satiation, or fullness, and reduced calorie intake.
Caffeine as an appetite suppressant may only work for a short while. Also, because it’s easy to think like you’re thirsty when you’re really hungry, drinking caffeinated beverages to satiate the hunger may help quell the appetite. 
A study from Duke University indicates that caffeine makes you feel hungry because it triggers more insulin secretion. This causes blood sugar levels to go down, which apparently increases the feeling of hunger. 
The Journal of the Academy of Nutrition and Dietetics published a study showing how small amounts of caffeine can cause people to consume less food.  When participants were asked to ingest 1 mg/kg of caffeine, they were found to have consumed 10 percent less or 70 fewer calories in a breakfast buffet. However, the effect was transient and the participants did not so much feel the effect in their appetite. The study concludes that caffeine is “not effective as an appetite suppressant and weight-loss aid.” In conclusion, this study shows the following: 
the participants, later on, made up for the decreased intake in the morning
they did not feel any different from their regular breakfast
the individual participants’ BMI did not show any impact of caffeine as an appetite suppressant.
A couple of studies say that caffeine does NOT curb the appetite at all. [11, 12]
While various research and studies have been conducted on the subject, there’s nothing conclusive about caffeine being an effective appetite suppressant.
It’s safe to say at this point that if you wish to curb the appetite, you can stick to a healthy diet, regular workout, and this thing called discipline.
There are also other natural appetite suppressants which you can resort to. Oddly enough, this video says that drinking decaffeinated coffee works more effectively in losing your appetite than caffeinated drinks and caffeine pills.
(Of course, it’s a different story altogether if we’re going to talk about losing weight. Because caffeine does certainly help in this area! There are 3 ways caffeine boosts your metabolism, and we’ve covered it at length in the linked article.)
No matter what its impact on your appetite is, you can always treat your favorite cup of Joe or other forms of caffeine as just that - a caffeine fix.
And if we ever find out in the future that caffeine is indeed the best appetite suppressant, then it’ll be a pleasant icing on the cake!
Erectile dysfunction. In combination, those are two of the ugliest words known to man. But can caffeine help you get it up?
Science hasn't found the definitive answer to this question, but one study concluded that fewer men who consume caffeine have problems performing. The study said:
Caffeine intake reduced the odds of prevalent ED, especially an intake equivalent to approximately 2-3 daily cups of coffee (170-375 mg/day). This reduction was also observed among overweight/obese and hypertensive, but not among diabetic men. Yet, these associations are warranted to be investigated in prospective studies