We know that to lose weight we need to eat fewer calories than we burn. A safe estimate for weight loss is no more than 1lb (~0.5 kg) per week. Since 1 lb. of fat provides ~3500 calories, target a deficit of 500 calories per day for healthy weight loss.
Studies show, that if we change the ratios in our meals - it can offer a short-term boost. In 2013 after reviewing 16,000 studies, Sweden's Council on Health Technology. Assessment concluded low-carbohydrate diets are more effective as a means to reduce weight than low-fat diets over short periods of time.