Given your height, I would just eat a healthy diet and let exercise do the work. Seems to me you don t really need to loose weight, you need to firm up what you have. The harder and longer you work out the more calories you allow yourself. This establishes goals that work. Good Luck.
Twenty pounds is nothing. That should come of pretty quickly. But the rule is, don t lose more than two pounds per week. No radical diet needed. 30 minutes 3 times per week is not enough. Should be 45 minutes every day. Same time every day. But don t kill yourself. A fast walk is perfect. No animal fats. Plenty of whole grains. Dried and fresh fruit. Lots of veggies. Fresh lowfat yoghurt is good. Juices. No soda pop whatsoever, Even the diet dreck. Cut that out now! Plenty of water. Whole grain rice, legumes, olive oil. No margerine of any kind for the rest of your life. No store-bought bread, unless it says no preservatives . The same with fast food. After you get down to 130, then you can have the occasional steak or pork chop. No harm. BTW, your body will never refuse to lose weight. However,if you starve yourself, your body can switch into the famine mode and really work to conserve calories. And if you crash to your desired weight, in this case 130, when you go off the diet, your body will start storing calories like crazy since it s afraid another famine might be right around the corner. That s why crash diets never work. Also, vigorous exercise acts as an appetite suppressant. That s why I think it s important every day, at the same time every day. After you get there, cut back and take a rest day every week.