Does skipping breakfast lead to weight gain?

Does skipping breakfast really make you gain weight? The observational evidence says yes, but with a catch.

Large-scale observational studies consistently find that people who skip breakfast are more likely to be overweight or obese. A 2023 meta-analysis of 40 studies involving over 323,000 children and adolescents found that breakfast skippers had a 59% higher odds of being overweight or obese compared to regular breakfast eaters [1]. Similarly, a 2021 review of longitudinal studies in adults found that skipping breakfast on three or more days per week was associated with an 11% increased risk of developing overweight or obesity [2]. These associations hold across different age groups and cultures: a study of middle-aged men in Saudi Arabia found that breakfast skippers had a significantly higher average body mass index (27.1 vs. 26.2) [5], and a study of Korean adults found that skipping breakfast was one of the factors linked to weight gain in both men and women [7].

However, these studies are observational, meaning they can show a link but cannot prove that skipping breakfast causes weight gain. People who skip breakfast may also have other habits that contribute to weight gain, such as eating more calorie-dense foods later in the day, getting less sleep, or being less physically active. For example, a 2022 study found that insufficient sleep and skipping breakfast together were associated with a 25% higher odds of overweight/obesity in children, compared to those with sufficient sleep and breakfast [6]. This suggests that breakfast skipping is often part of a broader pattern of unhealthy behaviors.

But when scientists test it in controlled experiments, skipping breakfast doesn't directly cause weight gain.

The strongest evidence for cause-and-effect comes from randomized controlled trials (RCTs), where people are randomly assigned to eat or skip breakfast and then followed over time. A 2021 systematic review and meta-analysis of 10 RCTs (lasting from 6 days to 12 weeks) found no significant difference in body weight, body mass index, body fat percentage, or waist circumference between those assigned to eat breakfast and those assigned to skip it [8]. The average difference in weight change was only 0.17 kg (about 0.4 pounds), and the confidence intervals included zero, meaning the result was not statistically significant.

Why the contradiction with observational studies? One explanation is that people who naturally skip breakfast may have different lifestyles than those who don't. When researchers force people to change their breakfast habits in a controlled setting, those other lifestyle factors (like total calorie intake, physical activity, and sleep) are often accounted for or kept constant. This suggests that skipping breakfast itself is not a direct cause of weight gain, but rather a marker for other behaviors that do promote weight gain. For instance, a 2021 study found that skipping dinner, not breakfast, was a stronger predictor of weight gain in university students [3], and a 2022 study found that eating lunch late (after 12:34 PM) was associated with higher BMI and obesity risk, independent of breakfast habits [9].

So what should you do? Focus on overall diet quality, timing, and physical activity, not just breakfast.

The evidence suggests that whether you eat breakfast is less important than what and when you eat overall, and how active you are. A 2022 study found that moderate-to-vigorous physical activity (MVPA) can reduce the negative association between skipping breakfast and excess weight in children and adolescents [10]. In other words, if you skip breakfast but are physically active, the impact on your weight may be lessened. Similarly, a 2024 study in adults with type 2 diabetes found that nutritional management (a personalized Mediterranean/DASH diet) led to significant improvements in weight, blood sugar, and cholesterol, regardless of whether participants initially skipped breakfast [4]. By the end of the study, the percentage of participants skipping breakfast dropped from 77% to 14%, but this was part of a comprehensive dietary intervention, not a standalone change.

The bottom line: If you skip breakfast but eat a healthy, balanced diet later in the day and stay active, you are unlikely to gain weight from skipping breakfast alone. However, if skipping breakfast leads you to overeat later, make poor food choices, or be less active, it could contribute to weight gain over time. The most reliable approach for weight management is to focus on overall calorie balance, meal timing, and a healthy lifestyle—not to fixate on any single meal.

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