I think the most important thing involving weight is the food reward aspect. If you have any inkling that you're overindulging, try to separate the foods you eat a bit (i.e. if you're eating potatoes and butter don't mix them together, just eat the potato and then the butter separately). I know nuts can cause excess calories to pile up, so you may want to drop that if you do eat them. Otherwise I think you should just ease up a bit and just continue down this road before making any critical decisions. For all you know it could be a minor fluctuation--which is exactly what 3 pounds sounds like. Above all make sure you're enjoying yourself and feeling good. All the best!

First couple of weeks I wouldn't worry about it. Get use to your new lifestyle for a while. After a couple months if your still gaining or not happy with how things are going you may consider some adjustments. BTW 3 pounds can easily be fluctuations in water weight.

I have had the exact same reaction myself. I just started Paleo two weeks ago, 80-20, being also full cream and chocolate or homemade nut bar. I weighed myself this morning and I am 2 pounds heavier. I am obese btw which makes the scale even more devastating. My portions are considerably lower than pre-paleo as I did not feel hungry after 3 days in so i decreased my portions. My activity is rather light as I am taking one day at a time since starting paleo so I exercise just 30 minutes a day. When I saw the scale today, I immediately wondered what am I doing wrong. But then I listened to my body while working out and honestly I feel more flexible and I am more alert than usual. There is definitely a change going on in my body, I just dont know what that change is. I have decided to let go of the scale for another three weeks and then weigh myself then.

If you eat a lot of fatty foods you will get a lot of calories. Enjoy the freedom from restriction for now. You have been deprived for years. Don't worry too much about overindulging for the time being because you'll reach a point where the fat doesn't seem so special anymore. Meanwhile, toss out your scale because eating nutrient-rich foods is going to build bone and muscle which weighs more. Lift some weights, run some sprints, walk and cycle to get around, get some sunshine and plenty of sleep and it'll all work out.

I wouldn't worry about those numbers. Sometimes a little weight is needed to be gained to be optimally healthy, and 120s is certainly not a big number of 5'6" (I'm 5'7", 24, and 150 lbs, but I've got a large frame).

Fun story: When I was at my lowest weight (and the height of my disordered eating behavior), I was 140 lbs and trying desperately to reduce my body fat percentage so that my hip-to-waist ratio would be in the "ideal" range. I was sitting at .78 (with the "ideal" range being .8 or higher). I have to say I was a slave to conventional medical/dietary advice at the time. I could not seem to lose those extra inches where I needed to. My butt was flat and I'm quite positive there wasn't any more fat I COULD lose from my hips. Well, I eventually gave up my striving and started nourishing myself with real portions of real food. Over the next six months I gained 10 lbs, then I maintained it for a few years before transitioning to my currently high-fat, moderate-protein, moderate-carb WAPF/Primal eating style. I recently decided to measure myself, and while my numbers are up almost everywhere from where they were at my lowest, my hip-to-waist ratio is above .8 now.

Melissa McEwen (huntgatherlove.com) has talked about this on her blog and several places in the community. Even Mark Sisson had a post on this a while back. When women store DHA, it is stored in their lower body, which is optimal for fertility. In fact, when women HAVE this fat (and by comparison little-to-no visceral fat), it is a marker for good health.

Several women in this community (including myself and Melissa) have experienced this "redistribution" of fat to more favorable places since eating this way. This may be what's going on with you.

ALSO! As a last caveat and warning. You're 18. You're not done growing, so the scale WILL go up over the next 5 years or so even if you don't do paleo. It's sad to see so many young 20-somethings worry about the "Freshman 15" as if it's a bad thing, when in reality, it's just part of growing up. I gained 40 lbs in college, but half of it was lean body mass, and I wasn't even exercising! Same happened with my husband. He was athletic (and scrawny) all through high school but once he got to college he hit a growth spurt and "filled out" into a more muscular, adult body.