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Does Late Night Snacking Contribute To Thyroid Weight Gain?

Learn how meal timing affects thyroid-related weight gain.
Does Late Night Snacking Contribute To Thyroid Weight Gain?
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People often follow strict rules, such as not eating after a specific time at night to avoid increasing their waistline. Yet, there is some debate over whether meal times matter when it comes to scientific studies about meal times and weight gain. Ahead, a look at whether eating at night contributes to thyroid weight gain.

Hypothyroidism and weight gain

Weight gain is one of the most prevalent symptoms of hypothyroidism. Hypothyroidism is the condition of an underactive thyroid gland, meaning that the thyroid does not produce enough thyroid hormone to support the body’s metabolic demands. Thus, your metabolism slows. 

Metabolism is essentially the term used to describe all of the chemical reactions the occur inside your body. These reactions include maintaining your cells, supporting your cellular functioning, and growth and development. People with too little thyroid hormone experience hypometabolism, which is characterized by:

  • A decreased resting energy expenditure
  • Increased cholesterol levels
  • Reduced breakdown of fats (lipolysis)
  • A lower rate of gluconeogenesis (the process of making sugars for energy)

Ultimately, hypometabolism causes weight gain because the body cannot use calories fast enough to support energy needs. Thus, we store excess energy in the form of fat.   

However, the relationship between hypothyroidism and weight gain is not necessarily straightforward. Indeed, fat accumulation is more likely in people with a slower metabolism. Still, an excess collection of salt and water may also contribute to more weight. Treating hypothyroidism with thyroid hormone replacement medication can help people lose some weight, but often weight gain is caused by several factors. So, thyroid treatment alone will not always return you to your original weight.

The circadian rhythm and metabolism

We know that the thyroid is directly involved with metabolism regulation. And we also know that many factors can contribute to weight gain, including our eating habits. Many people believe that eating after a set time, such as 8 P.M., will cause weight gain because of its effects on the circadian rhythm

The circadian rhythm is a 24-hour cycle that serves as our internal clock that tells our body when to perform certain functions. Specifically, this rhythm regulates our sleep-wake cycle and is directly influenced by light. 

We naturally enter our resting phase when it becomes dark outside. During the resting phase, the body is busy processing memories, storing energy, and cleansing the body. Our bodies do not require food during this part of the cycle and expect to be fasting. Indeed, our bodies naturally only require feeding during our waking, active cycle. When we eat closer to or during our resting cycle, it can throw off our metabolism and energy storage. 

Several studies aim to explore the relationship between eating time and weight gain, and the results are inconclusive. The results from one study of children found that meal timing does not affect weight gain. Children who ate before 8 P.M. did not have a lower rate of obesity than those who ate after 8 P.M. Additionally, the study finds that children who ate after 8 P.M. were not more likely to eat more compared to those who ate earlier.

On the contrary, some animal studies have suggested the opposite: mice who ate closer to or during resting hours had higher BMIs (body mass index) and were likely to eat more than mice who only ate during normal waking times. 


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What you eat matters just as much as when you eat

While there is still debate over whether timing directly causes weight gain, there is an agreement that what you eat matters. Regrettably, timing can affect our meal choices and the amount of food we eat. Thus, eating late at night may cause people to make poor food choices.

One study of adult participants found that people who ate later and closer to bedtime ate more calories than people who ate only during the day. Consuming excess calories leads to weight gain over time. Furthermore, people commonly eat foods higher in fat content and refined sugars closer to bedtime, contributing to weight gain. 

How to curb weight gain with hypothyroidism

Time-restricted feeding is a beneficial way to decrease weight and increase longevity. Thus, by following your circadian rhythm and eating only during the waking phase of your sleep-wake cycle, your body can fast during rest. Intermittent fasting is a natural way our body controls metabolism and is an increasingly popular strategy or diet solution to curb weight gain. Interestingly, fasting allows our body to enter alternative metabolic phases that rely more on stored energy sources instead of glucose. 

Aside from allowing your body time to fast, watching what you eat is essential. Because we often lean into sugary snacks closer to bedtime, limit sugary treats to earlier in the evening, or replace them with a healthier option like apple slices and honey. 

Finally, people with hypothyroidism require lifelong treatment with thyroid medication. Along with dietary and lifestyle changes, correctly taking your thyroid medication is vital to controlling your weight and managing other hypothyroidism symptoms that can slow you down.   

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Julia Walker, RN, BSN

Clinical Nurse

Julia Walker, RN, BSN, is a clinical nurse specializing in helping patients with thyroid disorders. She holds a Bachelor of Science in Nursing from Regis University in Denver and a Bachelor of Arts in the History of Medicine from the University of Colorado-Boulder. She believes managing chronic illnesses requires a balance of medical interventions and lifestyle adjustments. Her background includes caring for patients in women’s health, critical care, pediatrics, allergy, and immunology.

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