Nice going.
Little issue: I played with the first 5 weeks. It had me losing negative 269 pounds for January. The formula for total weight loss for the month takes the amount in cell B39 and subtracts the weight in cell B2. Since I hadn't entered anything in B39 yet, it read the value of that cell as zero. Hence the negative weight loss.
There's a fix somewhere, but it's a Friday after a hard week, and before a 3-week vacation. My brain is sleeping. All I can do to type.