To lose 40 pounds in 4 months you will have to lose 10 pounds per month which is a bit higher than the recommended weight loss rate up to 2 lbs per week. However, you can achieve it if you have to show up slim in an approaching family event. Following a low calorie diet combined with physical activity will help you achieve your goal. You can also choose weight loss programs that assure you a considerable amount of weight loss within a month. For example, Nutrisystem claims that it can offer weight loss up to 13 lbs and 7 inches in the first month through its newest launch FreshStart program. Have a look at http://prodiets.org/ that talks about Nutrisystem and its diet plans.
When trying to lose weight it is highly important that you set up a realistic goal in order to get motivated and stay on track. Losing weight quickly requires following an extremely low calorie diet which is not recommended by health experts. It is not recommended for a woman to eat below 1200 calories per day and men below 1600 calories. Dipping below the recommended range will bring in nutrition deficiency and associated health complications. In 4 months, you can lose up to 32 pounds or as much as 34 pounds. You may lose more than 2 lbs per week in the first few weeks of your diet plan. To lose 2 pounds per week you will have to eat fewer than 1000 calories than you burn.
Make smart choices when it comes to eating. Your daily diet should include mostly lean protein and plenty of fresh fruits and vegetables. Consuming minimum of 0.55 grams of protein per pound of body weight will keep you satiated and prevents you from losing muscle mass. Also include whole grains, low fat dairy foods and unsaturated fats in your daily diet so that you do not go low on nutrition.