A fixed-term attempt is built to end
Many weight-loss attempts are time-limited: six weeks, eight weeks or sometimes three months. When the period ends, daily life may continue much as before if nothing around it has changed.
Weight changes have many influences, and no single account of the body explains every situation. A short period does not necessarily match what daily life requires over the longer term.
That is why weight returning does not mean you tried too little. It may mean the approach did not fit the rest of your life.
