If you or your loved one works night shifts or rotating hours, you may have noticed changes in body weight or health. Many people who work outside of the typical 9-to-5 schedule struggle with weight gain. But why does this happen? Can working at night really make you gain weight?

In this article, we’ll explore the effects of shift work, its link to obesity, and what you can do about it.

What Is Shift Work?

Shift work means working hours that are outside the usual daytime schedule. This can include night shifts, early morning shifts, rotating shifts, or long working hours that change from week to week. Many industries and jobs nowadays require shift work so that workers are available 24 hours a day. For example, this may include healthcare professionals, factory workers, security guards, and delivery drivers. These irregular working hours can negatively impact overall working conditions and, in turn, affect workers’ health.

Does Shift Work Cause Obesity?

Obesity is a condition where a person has excess body fat, which can lead to serious health consequences and chronic diseases like diabetes mellitus, heart disease, sleep issues, and other poor health outcomes. Doctors often use something called body mass index (BMI) to diagnose obesity, and a BMI of 30 or higher is considered obese. However, BMI isn’t the only measure. To get a more accurate picture of a person’s health, doctors may also assess waist circumference, body fat percentage, and how fat is distributed throughout the body, since abdominal fat in particular is linked to higher cardiovascular risk.

Some research shows that shift work is linked to a higher BMI and an increased risk of obesity. This connection has led to growing interest in the relationship between shift work and obesity, particularly how irregular schedules may affect metabolism, appetite regulation, and sleep patterns. It’s important to remember that this doesn’t mean every shift worker will have a higher body weight, but it does mean that they face more challenges that can lead to weight gain. Below are a few possible reasons:

1. Shift Work Disrupts Your Body’s Internal Clock

Our bodies have a natural clock called the circadian rhythm. This clock tells us when to sleep, the sleep duration, when to eat, and when to be active. It’s based on light and dark cycles, or day and night. When you work at night and sleep during the day, it can cause something called circadian disruption.

This misalignment can affect your hormones, especially these ones:

• Melatonin — This hormone is responsible for sleep. More melatonin is typically released at night or when it’s dark out.
• Ghrelin — This is the hunger hormone, which tells your brain you’re hungry.
• Leptin — This is the fullness hormone that signals to your brain that you’ve had enough to eat.

Shift work may disrupt the body’s natural production of melatonin, which in turn can mess up how your body’s cells repair themselves and function. Over time, this may lead to the formation of tumors and certain cancers.

In addition, previous studies show that shift workers often have higher levels of ghrelin and lower levels of leptin, which means they typically feel hungrier and less satisfied after eating. This may lead to overeating and weight gain.

2. Poor Sleep Affects Metabolism

Shift workers often experience sleep deprivation or have poor-quality sleep compared to nonshift workers and day workers with a regular day shift. Insufficient sleep affects your metabolism and how your body handles glucose, or sugar. When your body can’t use glucose properly, it stores fat. This is called insulin resistance, and it’s a step toward prediabetes and type 2 diabetes.

Also, when you’re fatigued, your body tends to crave high-calorie, sugary, or fatty foods. That’s why you might reach for chips, soda, or fast food during a night shift. These foods are easier to grab, but they can lead to weight gain over time.

3. Lifestyle Factors and Shift Work

Shift workers often face many daily challenges that can make it harder to stay healthy, including:

Less Time for Exercise

After this type of shift, most people just want to sleep. Finding time or energy to exercise can be tough. Regular physical activity helps in preventing a number of health conditions and facilitates better sleep.

Eating on the Go

When you work odd hours, it can be harder to find healthy meals. Many shift workers rely on vending machines, fast foods, or microwave meals. These are often higher in calories, sugar, and unhealthy fats.

More Stress

Working at night or on rotating shifts can be stressful, and this added stress might increase a hormone called cortisol, which is responsible for fat storage, especially around the belly. Higher cortisol may also result in mood disorders like anxiety and depression.

How Bad Is Shift Work for Your Health?

Weight gain isn’t the only impact of shift work. It’s also been linked to higher risks of certain conditions, including:

• Cardiovascular disease, or heart disease
• Stroke
• Gastrointestinal issues, such as constipation and diarrhea
• Type 2 diabetes
• Hypertension, or high blood pressure
• Depression and anxiety
• Sleep disorders, like shift-related sleep disorder
• Certain cancers, particularly breast cancer

Keep in mind that just because you do shift work doesn’t mean you’ll develop these conditions. However, it does mean you should be aware of your health and habits.

Tips for Shift Workers

If you’re a shift worker or care for someone who is, here are a few tips to manage weight and stay healthy:

1. Prioritize Sleep

Try minimizing sleep disturbances and your exposure to light following a shift if you’re planning on sleeping afterward. Also, ensure you’re getting enough sleep, especially on your days off.

2. Plan Healthy Meals

Pack meals and snacks ahead of your shift to avoid vending machines. These food options should include protein and fiber, which help you stay full for longer. You may need to adjust your eating habits based on your work shift, but try to avoid heavy meals right before bed.

3. Move When You Can

Stretch or take short walks during breaks or between work responsibilities if you’re able to. Depending on your work environment, you may also be able to do quick or seated workouts with equipment like resistance bands or hand weights. Using the stairs instead of the elevator or parking further away so you have to walk can also add more movement into your day.

4. Manage Stress

You may find it beneficial to practice deep breathing, meditation, or journaling. Staying connected with friends and family can also keep you from feeling isolated. If you’re feeling overwhelmed, look for support groups dedicated to shift workers or employee assistance programs.

Talk to Your Doctor

If you’re struggling with weight and work shifts, talk to your doctor. They can help you understand your health risks and create a plan that works for your schedule. You might also be referred to a dietitian or sleep specialist.

While shift work can make it harder to stay at a healthy weight, the good news is that with the right tools and support, you can take control of your health and well-being. Understanding how your body works and making small changes can lead to big results over time.

Remember, you’re not alone. Many people face the same challenges. Start by talking to your doctor and taking it one step at a time.

Talk With Others Who Understand

MyObesityTeam is the social network for people with obesity and their loved ones. On MyObesityTeam, members come together to ask questions, give advice, and share their stories with others who understand life with obesity.

Does your current job have a shift work schedule? What tips do you have to balance your work and life responsibilities? Share your experience in the comments below, or start a conversation by posting on your Activities page.