As a formerly obese person myself, my recommendation is that she needs to take this slower if you want her to stick to it. New food + Crossfit at the same time may really be too much, especially if she has an eating disordered past.

When I made this really work, I got my food portion right for about a month before I jumped into exercise. Also, you may want to go 80/20 Paleo with her and allow some non-Paleo foods. Or maybe make some Paleo friendly things like almond butter brownies and macadamia nut cookies, Paleo pancakes, touches of what she's used to.

The other option is to cut everything completely out for 30 days, like a whole 30.

You really need to have a heart to heart with her regarding what SHE thinks will work for her best. Some people need to ease into a lifestyle change to make it stick and some people will take allowances like 80/20 and stretch them too far and end up not fixing anything at all.

Do not be judgemental. Deciding to make the change is a huge step. It can change your whole life. If you have been making excuses for other parts of your life based on being fat, it is very scary to decide to change that. Once your fat is gone, you have to figure out the other things. Losing weight can be extremely mental. You have to be ready for that. Going slow really helped me mentally keep up with the weight loss.

I'm new here, but I would say as someone who experienced hellish low-carb flu, explain it to her and why ultimately it's a good thing --even if you have to describe it as a "detox". My N=1 was that I felt so much better after getting off the grains alone after a couple of weeks, I was ready to pay attention to the rest of "it" (primal/paleo/whatever). And perhaps provide her w/ the links to all the discussions here about low-carb flu so she knows she's not alone. That helped me tremendously.

I'm fat too. I've lost 35 pounds though in the last 3 months and feel fantastic. At the beginning of summer I cut out all white food - rice, pasta, bread, potatoes, sugar. The first couple of days were HARD. Then I felt better and realized that carbs are addicting. If I cheated, I'd cheat for a couple of days. I would have to fast to break the carb-cycle. THEN I discovered Paleo. I way upped my meat and fat - WAY. I looked into Cross-Fit, but since I knew I couldn't even do one of the assessment skills, I passed. I found a knock-off of P90X called Supreme 90 Day (something or other) on Amazon. I have done it for 2 months and can do a push up! I have muscles! Doing cardio - the exercise all fat people are told they need to do - is hard on fat people, and we give up. Lifting weights and squatting is easy - we keep it up.

I think the exercise helped me to feel better thus making the "diet" easier. I would suggest that she does do both, but not Cross-Fit right away. My goal is join Cross-Fit by Christmas.

My first question would be how long has she been doing paleo? Even if it isn't a low carb form of Paleo most people switching from sad to paleo get the typical LC response to the transition. The headaches, tiredness, and crappy feeling will last for the first 1-3 weeks before the body really transitions from burning carbohydrates to burning fat. It's two different metabolic processes and takes the body some time to figure out what's going on.

The best thing to do is just stick it out... That's why the Whole9's Whole30 challenge is a good program. It forces people to stick it out past the low carb slump that usually comes with the switch.

Have you heard of AndreAnna's Life as a Plate blog? She was once morbidly obese - was once near 300 lb. - and now she is a fit and fierce Crossfitter who is all kinds of toned. Here are a few links from her inspiring story that you may consider sharing with your friend.

Most importantly, since your friend is still in the awful transition off of processed carbs, have her read AndreAnna's post about her own experience (it had me laughing because I could identify!): http://www.lifeasaplate.com/2010/10/13/the-plunge/

Her Crossfit Posts: http://www.lifeasaplate.com/category/healthfitness/crossfit/

Her Weight Loss Posts: http://www.lifeasaplate.com/category/healthfitness/weightloss/

Her before:

And her recently at a Warrior Dash (she's #56213):

I would say she should just eat as much or as little as she wants as long as it's paleo for now (except for fruit.) Also...for the transition...try some salty broths or just supplementing salt literally by eating it.

I second (or third?) the recommendation to have her avoid Cross-fit for now. Make sure she's getting good sources of healthy fats (pastured butter, pastured eggs, preferably grass-fed liver) ... and not trying to do this low-fat because that's been drummed into her head for years.

And have her check out paleo hacks ... let her know that there are other women who are or have been where she is (I've lost 100 lbs with more to go). It's not just for hard bodies ;).

When I am trying to convince obese people to try this diet, I always point out the main selling point that appeals to those who love food: You never have to be hungry or count calories.

If she needs to eat a little fruit to stay motivated, it is better than feeling like she can't stick with Paleo. Eventually she will reduce her carb cravings anyway. Too extreem and she could feel discouraged and never try it again.

when i first cut grains i was making almond crackers every day for about 3 weeks. i haven't made them since. change can happen with small steps.

I guess Im probably not doing it right but I didn't feel good on paleo until I started adding potatoes (about 4 small/ med per week) to my diet.

Going cold turkey isn't the only way. For some people it works best, and most people probably see more results faster (which can be very motivating for some people), but if it's too difficult to stick to it isn't a help, and there's a tendency to throw everything out the window and go back to total SAD.

"You" refers to whoever is making the dietary changes, not the OP specifically, since the OP is not asking for him/herself. These suggestions are based on my own experiences, as well as watching friends try to go paleo and get overwhelmed.

A gradual approach can be a much easier adjustment psychologically.

As more foods are eliminated, be sure adequate fat is included to encourage satiety.

Step 1: If necessary, learn to cook, and prepare more meals at home. Switch to paleo-appropriate oils when cooking at home. Integrate higher quality animal products and produce to the greatest extent that budget allows. Focus on low glycemic index fruits and veggies, but integrating some sort of real produce with each meal is a positive step if it isn't happening already. Use grains and legumes that have been properly prepared (soaking and so forth) WAPF style for all homecooked meals. These steps should be pretty painless emotionally - you're not eliminating anything, just laying a foundation for future changes.

Step 2: Eliminate gluten. Preferably don't use gluten-free replacements (especially processed) unless they're paleo.

Step 3: Eat meals at least several times a week that don't include grains, legumes, and/or dairy. Not all of them, but enough to psychologically adjust to the idea of meals without these things. Use only high-quality, full-fat, preferably fermented dairy products, and experiment with using non-dairy milks for some purposes.

Step 4: Eliminate grains and legumes.

Step 5: Eliminate processed sugar. Don't replace them with large amounts of other sweetener, whether natural or artificial.

Step 6: Go low carb if not seeing adequate results from changes thus far.

Step 7: Experiment with eliminating dairy, going strict Whole30, and so forth.

These steps aren't set in stone - they should be adjusted according to what the individual in question finds easiest to eliminate. If cutting dairy is easy for the person, then that's a good earlier step. If keeping dairy in the diet helps with compliance to the rest of the diet, keep it in until other addictions are dealt with.

Alternatively, do this backwards. Go strict paleo, then add stuff back in as needed until you reach a point where you feel you can handle it rather than going back to complete SAD. Then work towards gradual elimination of those crutches.

A very close family member has recently decided to follow this diet as well (and she's in almost the same boat as your friend).

To fight off the carb headaches, she would eat 1/2 an orange. This would help her over that hump without killing her progress.

She's 2 weeks in now, sans 16lbs of water and some fat weight, with no headaches, and surprisingly no severe "bad food" cravings.

I built a very custom template for her, the gist of which was to put her on a diet of whole, non-starchy foods, give her an overhead of about 200-calories over her BMR, and avoid "trigger foods" - foods that potentially motivate binges.