Hey Emelie -
I think the easiest way to answer this is to let Dr. McDougall. Here's what he has said on the subject:
These rich plant foods may account for a small portion of your daily food intake (less than 10 percent of your calories per day) but only after you have attained the level of health you are striving for. In general, these foods are more harmful than health-supporting. Never eat these foods if you have problems with your health that remain unresolved. They can easily add to your body fat. If you begin using this group of foods and find that you are also gaining weight or getting back some of your old ailments, then stop eating these foods immediately.
IIIA. High-fat plant foods contain large amounts of fat, and are very high in calories.
4. Nut butters (like peanut butter).
6. Seed spreads (like tahini).
8. Tofu (fiber has also been removed).
11. Soy "ice cream".
12. Coconut meat.
13. Chocolate (dairy-free).
So if you keep it below 10% and you may be ok.