Hi Jennifer, I would recommend some muscular endurance weight lifting a couple times a week.
A mix of upper and lower body exercises with reps in the 12-15 range (people training strength often work out in the 2-6 rep range, people looking to gain muscle mass, bodybuilders, often work out in the 6-10 rep range, and athletes looking to increase muscular endurance go for the 12-20+ rep range). Cardio is good for healthy circulatory function but you will mainly only burn calories while you are working out, while weight training keeps metabolic function higher, and thus burns additional calories around the clock, as it repairs broken down muscle tissue. You won't need to worry about getting bulky as the weight being moved with that number of repetitions is not in the hypertrophy (muscle growth) range, but the muscles will find some nice tone. Most women would have to work out at extreme levels to develop the hypertrophy that seems to worry them being perceived as unattractive. Female bodybuilders work out 2-3 hours a day, everyday, and do lower rep ranges. Plus some dudes dig a gal with a few muscles
A nice looking body takes a little effort. Body weight is just a number and will vary with an individuals bone density, levels of hydration, and the amount of muscle carried. Someone with a lower body weight may actually appear "fatter" (i.e. softer) than someone heavier who has more muscle tone and greater bone density, a by product of weight bearing exercises. The increase in bone density from lifting is also helpful for staving off osteoporosis which some women may be prone to in later years. Better to focus on how you look and feel about yourself, than some number on somebodies chart.
I'm no expert, but for someone who isn't diabetic, the Atkins diet doesn't seem very healthy for ones internals. And I believe Dr Atkins died from a heart attack. Whatever diet you undertake, remember that fruits, vegetables, and complex grain structures are required to maintain adequate levels of fiber intake, keeping the colon nice and healthy. Fruit and vegetables are required to offset the acidity of a diet based on meat and cheese, which despite providing adequate protein does not provide an environment in the body which is conducive to retaining muscle mass. Alkaline rich diets hold onto muscle mass more efficiently. Fruit and vegetables are required to maintain adequate vitamin levels. English sailors found that out the hard way and a diet that has low levels of complex carbohydrates, vitamins, fiber and antioxidants can be associated with certain types of cancer.
