Sometimes, There Are Plateaus and Huge Detours
You see Brittany plateauing at one point in the movie. She becomes frustrated when she can't seem to lose more weight and is stuck at 160 pounds. A weight-loss plateau is normal. "It is so much more than numbers on the scale or counting calories," registered dietitian and certified diabetes educator Rachel Stahl, MS, CDN, told POPSUGAR in a preview interview. "Factors like emotion, food sensitivity, physical activity, environment, and medications all can play a role, so it's important to address these in addition to diet." Also, Brittany surely gained muscle while training, and muscle is more dense than fat, so going by what a scale says isn't always an accurate depiction of your progress and internal health.
The biggest challenge of all was Brittany's injury that causes her to postpone running the New York City Marathon a full year. She trains too hard on a bad ankle, and her doctor tells her it's a fracture and that she'll have to be in a cast for weeks. Sometimes setbacks — huge setbacks at that — will interfere with your goals. Then, you have to adjust and make new ones.