The first question that needs to be asked is how many calorlies is your wife eating now? You may have calculated that she needs to be at 1200 to get to where she wants to be, but that doesn't mean that she has to, or even should, start there. If she drops cals to much from the beginning she will crash and burn.
You two can come up with a meal plan to fit 1200 cals. She just needs to eat mainly protein and complex carbs. So lots of veggies, and protein dense foods like lean meat, chicken and whey powder will be her staples.
"Heaven and earth shall pass away, but my words shall not pass away." - Matthew 24:35
"But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance: against such there is no law." - Galations 5:22-23