100 g of protein enough?

Maybe?

Basically, you want around a gram per pound of lean body mass. Without knowing your height and weight, it's hard to say.

You can use this set of calculators to estimate your lean body mass: http://www.fat2fitradio.com/tools/mbf/

http://www.jissn.com/content/7/1/7

"The ISSN has recently adopted a position stand on protein that highlights the following points [39]:

1. Exercising individuals need approximately 1.4 to 2.0 grams of protein per kilogram of bodyweight per day.

2. Concerns that protein intake within this range is unhealthy are unfounded in healthy, exercising individuals.

3. An attempt should be made to obtain protein requirements from whole foods, but supplemental protein is a safe and convenient method of ingesting high quality dietary protein.

4. The timing of protein intake in the time period encompassing the exercise session has several benefits including improved recovery and greater gains in fat free mass.

5. Protein residues such as branched chain amino acids have been shown to be beneficial for the exercising individual, including increasing the rates of protein synthesis, decreasing the rate of protein degradation, and possibly aiding in recovery from exercise.

6. Exercising individuals need more dietary protein than their sedentary counterparts"

It's reasonable... but as others have said, depends on a few factors.