1200 calories a day is a borderline starvation diet. Of course it's going to work in the short term because you are not consuming much food, but it is not going to work for long-term, sustained weight loss. This is what perpetuates the yo-yo dieting.
In my research I found a quote I love: "Your body is not a bank account, it's a chemistry lab." This means you can play the numbers game all you want (counting calories, subtracting exercise calories burned, etc.) but that's not it. What matters is the TYPE of calorie you put in your body: where it came from, what its purpose is, what it tells your body to do (i.e. store or burn fat).
Hormones are key to weight loss. And food sensitivities too, but based on what I've read, hormones are #1. It's sort of a tricky, complicated system that I understand from reading about it but could never explain to someone else. It's kinda like, your body gets used to having all this junk in the system (excess fat, sugar, pesticides and other toxins, antibiotics and nasty stuff from some commercial meat, etc) so the normal processes for burning fat are shut down. The hormones responsible for telling your body to burn fat are still in your body too, but because of the excess junk, your body doesn't listen to those hormones. So everything - excess hormones and excess junk - just keep circulating and circulating and you don't lose weight. By eliminating the junk you can allow your hormones to start doing what they are supposed to be doing.
I hate counting calories. I log my food but more to see if I react to a certin type of food, or my meal timings, or how I'm feeling when I eat. The macronutrients - protein, fat, carbs - are important, but IMO should not be the only thing you look at when trying to get yourself healthy. It's the MICROnutrients that are essential to weight/fat loss. Americans are known to be deficient in some key minerals, such as magnesium and vitamin D3. Also fiber is important to help with the elimination of toxins.
In all my research, the common things to do for sustained weight loss are:
1. Sleep between 7-9 hours per night (a lot of the hormone-balancing happens while you sleep, plus helps you deal with stress by lowering corisol levels [stress hormone])
2. Also stop eating about 2-3 hours before bed to give you body a chance to digest your food before you sleep, so during sleep your body is only doing repair work.
3. Exercise - but not necessarily a lot of cardio. Weight/resistance training is much better for you, as well as short bursts of high-intensity cardio. Think sprinting, not marathons.
4. Drink about half your body weight in water every day.
5. Eat organic whenever possible, or follow EWG's Dirty Dozen/Clean 13. When you eat meat, choose grass-fed and pasture-raised. Animals on convential farms have the potential to be filled with disease and terrible diets that they were not meant to eat.
6. Dietary Fat is not your enemy - the right kinds are essential for fat LOSS. Fat is needed to keep your brain clear and focused. (Personally I find if I don't eat enough fat at each meal, I'm hungry within 2 hours and I have some brain fog.)
7. Avoid processed foods, which includes seed oils. Oils that are heated during the manufacturing process are damaged by the time they get to you. And if you heat them up further, you're consuming a terrible substance that your body doesn't know what to do with.
8. Avoid GMO foods. Lots of research is being done in this arena, but anytime a food has been genetically modified, you're tampering with nature. If the molecular structure is changed, you're risking the chance that your body can't process it. If it's marked organic that means it's not GMO.
9. Avoid gluten. Avoid dairy, or favor full-fat/raw/grass-fed sources.
Some blogs/books I read a lot:(Keep in mind I tend to move in what could be considered "Paleo" circles, so if that's not your thing then we can agree to disagree)
Dark Side of Fat Loss ebook and Underground Wellness podcast by Sean Croxton (what got me started on my current health-nut ways, the ebook has tons of the chemical info on hormones)
FatBurningMan.com and podcast by Abel James (he's got such a dreamy voice!)
Practical Paleo book and BalancedBites.com by Diane Sanfilippo (this book also has tons of info on the hormones' role in the body)
Diane Sanfilippo and Liz Wolfe's podcast at BalancedBites.com
CaltonNutrition.com by Mira and Jayson Calton (they have a new book out that I'm definitely going to buy, otherwise I find the stuff on their website really informative)
MarksDailyApple.com by Mark Sisson (super smart dude who really gets into sciency things sometimes)
whole9life.com and the Whole30 by Dallas and Melissa Hartwig
KrisCarr.com (this woman is not Paleo, she's living with an incurable form of cancer and has mostly healed her body with a vegan diet. I am in awe of her)
GreenLemonade.com - tons of smoothie recipes (I start every day with 10 minutes of yoga and a smoothie)
Currently I'm following JJ Virgin's Virgin Diet to see if I have food sensitivities.