Fragmented Sleep and Weight Gain: A Bidirectional Link

Obesity and sleep deprivation…go hand-in-hand? It looks that way.

In recent years, researchers have uncovered a compelling relationship between circadian rhythms, sleep quality, and body weight. Not only can poor sleep patterns contribute to weight gain, but excess weight can, in turn, worsen sleep quality. This understanding of a bidirectional connection is gathering momentum as clinicians and researchers begin to view sleep not as a passive process, but as an essential part of metabolic health.

Modern Life and the Rise of Two Epidemics

The rise in obesity is well-documented: in the United States, adult obesity increased from 22.9% in the early 1990s to nearly 40% by 2014. During this same time, the average amount of sleep people reported getting declined. The proportion of U.S. adults sleeping less than the recommended seven hours per night increased from 26% in 1998 to 35% in 2005.¹ According to the most recent polls from the Centers for Disease Control (CDC), up to 46% of adults are not getting adequate sleep.² 

This parallel rise has led scientists to examine the connections between the two. What they’ve found is that the relationship is more than a coincidence. Inadequate sleep (and more specifically, misalignment of the body’s circadian clock) can disrupt the hormonal and metabolic systems that regulate hunger, energy use, and fat storage.

Your circadian rhythm is your body’s internal clock that regulates sleep-wake cycles and other biological processes over a 24-hour period. When this rhythm is thrown off, it can impact everything from hormone production to how efficiently your body uses energy.

How Deprived Sleep Impacts Weight-Gain

Short sleep duration (fewer than seven hours per night) is consistently linked with a higher risk of obesity. Experimental sleep restriction has shown measurable effects on hormones involved in appetite and weight regulation. Ghrelin, the hormone that stimulates hunger, tends to rise with sleep deprivation. At the same time, leptin, the hormone that signals satiety, drops. Inadequate sleep impairs insulin sensitivity, promotes salt retention, and raises levels of inflammatory markers, all of which contribute to metabolic dysfunction.³

But the mechanism isn’t purely hormonal – cognitive and neural changes play a role, too. When we’re sleep-deprived, the brain’s reward system becomes more sensitive to food stimuli, especially high-fat, high-sugar options. Studies have shown that regions of the brain involved in pleasure and reward become more active in response to food cues after inadequate sleep.⁴ 

At the same time, the parts of the brain responsible for decision-making and impulse control are less active. This means that not only are we more drawn to tempting foods, but we’re also less able to resist them. The result is an increased drive to eat even when we’re not physiologically hungry, often leading to overeating, nighttime snacking, or choosing nutritionally poor foods that contribute to weight gain.⁵ 

Circadian Rhythm Adds an Extra Layer

How much sleep we get is one thing. When we get that sleep, is another. 

Circadian misalignment occurs when behaviors such as eating and being awake happen at times the body’s internal clock expects sleep, and it’s common in people who work night shifts, travel across time zones, or frequently stay up late with screen time or social activities.

Even in healthy adults, circadian disruption can have noticeable metabolic consequences. One study found that when people are awake and eating at times the body expects to be sleeping, their bodies become less efficient at burning energy, reducing total 24-hour energy expenditure by about 3%, or roughly 55 calories per day.⁶  That might sound small, but over time, even slight drops in energy use can contribute to gradual weight gain.

Some may argue that staying awake longer increases energy expenditure, and that may be true, BUT…

This slight increase doesn’t make up for what happens next. When we’re sleep-deprived, we tend to eat more – about 250 additional calories per day, on average, according to researchers. In other words, we end up taking in much more energy than we’re burning. Over time, this imbalance adds up and can lead to weight gain.⁶ 

When the Table Turns

Obesity itself can impair sleep quality, creating a self-reinforcing loop.

Individuals with obesity are more likely to suffer from sleep disorders such as obstructive sleep apnea (OSA), insomnia, and restless legs syndrome (RLS). These conditions can significantly reduce sleep quality and duration, even when individuals spend adequate time in bed.

For example, OSA causes repeated interruptions in breathing during sleep, fragmenting rest and lowering oxygen levels. This condition is significantly more common among individuals with higher body mass index (BMI), and it worsens as obesity increases.⁷ 

The obvious consequence is that sleep disruptions make you tired. Fragmented and insufficient sleep also alters glucose metabolism, increases insulin resistance, and raises evening cortisol levels, all of which can promote fat storage. Poor sleep also affects appetite-regulating hormones, like ghrelin (hunger) and leptin (satiety), which may lead to overeating or late-night snacking, as we mentioned earlier.

The very sleep disturbances that stem from obesity can make weight loss even harder to achieve.

The Vicious Cycle

Poor sleep drives weight gain through hormonal changes, reduced impulse control, and increased caloric intake. At the same time, excess body weight contributes to sleep disorders, inflammation, and physical discomfort, further diminishing sleep quality. This cycle can have cascading effects on overall health, and those getting caught in it are at greater risk of developing type 2 diabetes, cardiovascular disease, and mood disorders.

The link is particularly concerning when sleep loss starts early. Adolescents and young adults who chronically undersleep are more likely to gain weight over time and develop metabolic issues later in life. The earlier this cycle begins, the more difficult it becomes to reverse.

The Benefit of Multimodal Treatment

Integrating sleep assessment into weight management could uncover a hidden factor that’s quietly working against many patients, especially after bariatric surgery. Even with proper nutrition and movement, poor sleep can limit progress. Holistic treatment plans that address not just diet and exercise, but also the quality of restorative sleep, can amplify the hard work and commitment that go into weight loss surgery.

Sleep is often treated like a luxury, but it’s a biological necessity that directly impacts metabolism, appetite, food choices, and long-term weight regulation. Circadian disruption and poor sleep are metabolic stressors that can stall progress and increase the risk of obesity-related conditions.

Some practical steps to a better snooze include:

• Sticking to a consistent sleep schedule, even on weekends
• Avoiding late-night eating and screen time
• Creating a cool, dark, and quiet sleep environment
• Limiting caffeine and alcohol intake before bed

At VIPSurg, we recognize the effort it takes to pursue bariatric surgery – the appointments, the prep, the healing, the lifestyle changes. You’ve already made a powerful commitment to your health. Let’s make sure nothing, not even poor sleep, stands in your way.

1. Cooper, C. B., Neufeld, E. V., Dolezal, B. A., & Martin, J. L. (2018). Sleep deprivation and obesity in adults: a brief narrative review. BMJ open sport & exercise medicine, 4(1), e000392. https://doi.org/10.1136/bmjsem-2018-000392. 
2. CDC. (2024, May 15). FastStats: Sleep in Adults. CDC. https://www.cdc.gov/sleep/data-research/facts-stats/adults-sleep-facts-and-stats.html.   
3. Cooper, C. B., Neufeld, E. V., Dolezal, B. A., & Martin, J. L. (2018). Sleep deprivation and obesity in adults: a brief narrative review. BMJ open sport & exercise medicine, 4(1), e000392. https://doi.org/10.1136/bmjsem-2018-000392. 
4. St-Onge, M. P., Wolfe, S., Sy, M., Shechter, A., & Hirsch, J. (2014). Sleep restriction increases the neuronal response to unhealthy food in normal-weight individuals. International journal of obesity (2005), 38(3), 411–416. https://doi.org/10.1038/ijo.2013.114. 
5. Greer, S. M., Goldstein, A. N., & Walker, M. P. (2013). The impact of sleep deprivation on food desire in the human brain. Nature communications, 4, 2259. https://doi.org/10.1038/ncomms3259. 
6. Chaput, J.-P., McHill, A. W., Cox, R. C., Broussard, J. L., Dutil, C., da Costa, B. G. G., Sampasa-Kanyinga, H., & Wright, K. P. (2022). The role of insufficient sleep and circadian misalignment in obesity. Nature Reviews Endocrinology, 19, 82–97. https://doi.org/10.1038/s41574-022-00747-7.
7. Figorilli, M., Velluzzi, F., & Redolfi, S. (2025). Obesity and sleep disorders: A bidirectional relationship. Nutrition, metabolism, and cardiovascular diseases : NMCD, 35(6), 104014. https://doi.org/10.1016/j.numecd.2025.104014.