A few months ago, I had a post on the relationship between height and satisfaction with life. It's possible to look at the relationship between weight (relative to height) and satisfaction with life using the same data set. From the height and weight that people report, you can calculate their Body Mass Index. According to the Centers for Disease Control standards, a BMI of 18.5 or less makes you underweight, 18.5-25 is normal weight, 25-30 is overweight, and more than 30 is obese.
For men, the maximum average reported satisfaction with life occurs at 26.6, a little above the average BMI for men (27.3). For women, it occurs at 22.3, which is significantly below the average BMI for women (25.9). To translate that back into everyday terms, someone who is 5'4" and weighs 130 pounds has a BMI of 22.3. I also looked at the range of BMI values for which satisfaction is close to the maximum. The definition of close is necessarily arbitrary--I made it .01 on a 4 point scale. For men, average satisfaction values are "close" for BMI values between 24.4 to 29.3. For women, they are close in the range 20.4 to 24.6. So overall, the men who are most satisfied with life are those who are moderately overweight by the standard definition; the women who are most satisfied are in the "normal" range.