As was already mentioned, yes it is. However, it is not a wise idea to use coffee to suppress your appetite. The following are ingredients in coffee and some can cause other problems for your health :
2,3,5-TRIMETHYLPHENOL
2-ETHYLPHENOL
2-METHOXY-4-ETHYLPHENOL
2,4-METHYLENEPHENOL
DICAFFEOYL-QUINIC ACID
4-ETHYLPHENOL
4-METHOXY-4-VINYLPHENOL
ACETALDEHYDE
CAFFEINE
CAFFEOL
CAFFEOYL-3-QUINIC ACID
CAFFETANNIC ACID
CHLOROGENIC ACID
CITRIC ACID
DATURIC ACID
GUAIACOL
HYPOXANTHINE
ISOCHLOROGENIC ACID
PUTRESCINE
SCOPOLETIN
SPERMIDINE
SPERMINE
SUGARS
TANNIC ACID
TANNIN
THEOBROMINE
THEOPHYLLINE
THIAMIN
TRIGONELLINE
XANTHINE
Coffee reduces the absorption of important minerals, for example, iron, to be reduced by about 40% for up to 4 hours after consumption.
Even if you don't have severe reactions to caffeine it still can cause damage, you just won't know it for years. It reduces absorption of many important nutrients and iron in particular. More than 1/2 cup consumption of coffee a day, for a pregnant woman is enough to raise the risk of miscarriage. There are other, safer appetite suppressants and caffeine is best left alone.
Riffraff:
Yes, I know that. However, studies back as far as the 80's have shown that anything more than 1/2 a cup increases problems significantly. Recommendations aside, it is still dangerous as studies have shown. I am a childbirth educator and this is what I teach in my classes.