To loose weight in a healthy manner you need to make a deficit of 500-1000cals a day, for it to equal 1-2pounds weight loss in a week.
Your friends BMR is: 2100 (
http://www.nutritiondata.com/tools/calories-burned)
She can either cut 500 from her food or burn 500 or do a combination of the two. DO NOT go under 1200cals, in this case, do not do a deficit of more then 900cals. This will work against you in the long term, as your body will think its in a starvation situation and will start workinging more efficiently - unfortunally for us this means getting used to function on less calories and adapting. This comes from own experience, when i was living off 800-1200cals, exercising, and not loosing anything for a month.
Again, your body is very adaptable. For example, if your going to jog every day for 45min, the muscles you constantly use will get adapted and get more efficient - hence you'll burn less calories. People say you should take days off as this make it give it your all(mentally) on the non rest days, gives your body time to recover and build itself back, so there is no physical barrier to doing you best on non-rest days.
As for sugar spikes etc....it doesnt matter what you put in you if you just want to loose weight as long as you keep end up with a calorie deficit I lost weight on (half whenever I had one, guilt would not let me finish) chocolate criossants and choclate and other sweets. However,you are creating suger spikes and your depriving your body of nutrients which will make cravings and hunger much more elevated. Furthermore, only having sugars/carbs in your diet encourages your muscle to break down - and thats the last thing we want. So lots of vegetables, whole grain(half a cup-one cup a main meal), lean meat and healthy fats - the fats actually really help you feel satisfied for longer and promote the breakdown of bad fat in your body. And my best tip for meal time: herbal tea with every meal! It fils you up, makes you eat slower, makes sure your hydrated so you dont mistake thirst for hunger.
Hope all that helped!