Coffee has more caffeine than black or green tea. (Photo by alex-s)
In my previous post on the subject, I mentioned I would buy decaffeinated green tea to see how much of the appetite-reducing effects were due to the caffeine content of green tea. Unfortunately, the only thing I was able to find is decaffeinated black tea (which was ridiculously expensive, by the way). I haven't got around to really experimenting with it yet, so for the past week I've been drinking coffee instead.
My experiences with coffee suggest that caffeine is a big contributor in the reduced hunger effect. A rather modest amount of coffee will do the trick for me, whereas several cups of tea are needed to really see the benefits. This would fit in well with the fact that coffee contains more caffeine than tea.
Coffee seems to be especially useful in the morning, when just one cup is enough to suppress appetite, boost mood, increase energy and improve concentration. It is also helpful with what I call psychological hunger: when I smell all those delicious freshly baked bagels and sandwiches and see other people having their breakfast, the smell and taste of coffee alone is enough to keep me from breaking my fast. It's almost like cheating the brain to make it think I've eaten breakfast as well.
The same problems I have with drinking tea later during the day are apparent with coffee, too. Near the end of one fast, I drank a very large mug of coffee to see what happens. At first, I noticed a considerable reduction in the feeling of hunger and a slight increase in energy. However, it quickly turned into a nauseous feeling, fatique, and lack of concentration. I also noticed my hands were shaking quite a bit. As noted earlier, there was a similar (though not as strong) an effect with black tea, which has more caffeine than green tea but less than coffee. Again, this fits well with the caffeine hypothesis.
What surprised me somewhat was that so far, coffee has given the best results - when consumed in moderation. I'm a big fan of tea, but when it comes to improving concentration and getting an energy boost, coffee is definitely the winner. It really does help to kick things off in the morning. One small cup is enough for me, though, and in the afternoon it looks like I might have to stick to one or two cups of tea to avoid the negative effects.
For more information on tea, coffee and intermittent fasting, see these posts:
Controlling Hunger During a Fast: Does Decaffeinated Tea Help?
The Psychological Effects of Intermittent Fasting
Dental Health Effects of Green and Black Tea
Green Tea Reduces the Formation of AGEs