That's if you believe a new study from Cornell University, which found that people tend to weigh a little bit more on Mondays than they do on Fridays. The logic is pretty obvious: The weekend is our time to rest, maybe skip the gym and sleep in, grab an indulgent brunch, or just generally take it easy.
The study examined 80 adults who were categorized as weight losers, weight maintainers, and weight gainers, according to the relative changes they experienced over time. On average, people in all three groups weighed the least on Friday mornings and the most on Sunday nights. (Mental note: Hide scale on Sundays). The crucial difference was that the weight losers immediately started dropping pounds on Monday with a steep downward slide until Friday, while weight gainers had a much gentler slope.
So, it's normal for your weight to fluctuate a little bit throughout the week. The study also suggests that people who are watching their weight don't need to concentrate on those weekend off-days, but rather focus on what they eat during the week.
Of course, if weight loss were as simple as eating well during the week, we wouldn't have a $60 billion diet industry. It's worth noting that the data in this study was drawn from four previous surveys in which participants self-recorded their weight each morning before breakfast. Individual factors, like genetic obesity, illness, and medications that might alter metabolism, weren't taken into account. Nor did the study consider the participants' diets.
Out of the 80 individuals surveyed, only 10 were classified as gainers, and 18 as losers. The researchers admit, "Our sample size of the gain group was small, which limits the generalizability of the results and highlights the overall challenge of learning more about weight gainers." So, maybe it's worth taking this with a tiny grain of Sunday-night salt.
What is clear, however, is that minor gains on the weekends are normal, reversible, and shouldn't discourage anyone monitoring their weight. The key finding was the level of compensation that differentiated those who lost weight from those who gained. Weight losers didn't yo-yo so much as see a regular and rhythmic rise and fall in their numbers. Weight gainers' stats were more unpredictable.
The takeaway? If you're watching your weight, it's important to be consistent but flexible with your meals, and allow for a little indulgence. As our own Kelsey Miller has said about her anti-diet project, the idea of "good" and "bad" foods and an "all or nothing" mentality isn't conducive to sustained weight loss. What matters is long-term commitment to better eating and exercise habits during the week than can compensate for rich foods and weekend wavering.
Have your cake (any day of the week), and don't feel bad about it.