For obese women between 20 and 45 years old, losing weight through a low-calorie diet combined with aerobic and strength training reduces overall weight and waist size, but does not lead to different final BMI outcomes depending on whether weight is lost quickly, moderately, or slowly.

Among young women with obesity, a four-week program of moderate aerobic and strength exercise was linked to a small decrease in body mass index, while those who did not exercise saw a small increase.

Over four weeks, a combination of moderate aerobic and strength training led to an average loss of 3.6 kilograms of body fat in young women with obesity, while those who did not exercise gained an average of 1.56 kilograms of fat.

For women who aren't severely obese, losing fat depends only on eating fewer calories — it doesn’t matter if you cut those calories through diet alone or by combining diet with cardio, as long as the total calorie drop is the same.

When obese women eat extremely few calories (under 800 per day), they sometimes gain belly fat, lose muscle, and don’t lose much fat—making it worse than eating a little less.

In young women with a BMI between 25 and 27, participating in supervised group aerobic exercise three times a week for 12 weeks leads to measurable decreases in body weight, waist size, and body fat, along with an increase in muscle mass.