Updated May 27, 2015.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Thyroid patients often struggle with weight gain, or difficulty losing weight. You've read my book - The Thyoid Diet -- and you've tried to figure out which is the best thyroid diet to help you finally get control over the weight loss battle.

While you’re laying awake at night, pondering how to tackle the issue, you realize you’re hungry. A small snack might be just the thing, and off you go to the kitchen.

Any harm to that? The answer is probably yes.

Whether you’re doing the Autoimmune Paleo diet, or eating gluten-free  -- what you eat can be important. But a new study suggests that when you eat could be as important as what you eat.

THE CLOCK IS TICKING...

Timing appears to be an important factor in eating for health. Powered by genes associated with proteins, circadian rhythms cycle our bodies each day through 24-hour phases of sleep and wakefulness, digestive, hormonal, cardiac, and other activities.

Almost a decade ago, researchers found that a gene related to our circadian clock plays a role in metabolism and weight gain. Important because it identified a factor beyond calorie intake as a player in maintaining weight, the study fueled research to look at the relationship between time of day, eating patterns, and weight gain.

In 2012, researchers at the Salk Institute for Biological Studies conducted animal studies to evaluate whether time-restricted eating played a role in weight gain.

The experiment looked at:

• Animals that performed no exercise and ate high calorie food at will
• Animals that performed no exercise and ate high calorie food only during an eight-hour period of time each day

Interestingly, this study suggested the following:

• Those that ate at will gained weight, and developed symptoms of obesity, and diabetes.
• Those on a time-restricted diet did not gain weight or develop disease symptoms. This group also showed improved motor coordination.

Building on these results, scientists expanded their tests to weigh timing and nutrition more heavily against circadian rhythms. In a study lasting 38 weeks, 400 males were broken into groups fed different diets like:

• Kibble
• High fat foods
• High-fructose foods
• Foods containing high fat and high-sucrose

Within each group, some were allowed to eat at will, while others ate on a time-restricted schedule. From earlier research, the outcome  of this study was predictable. Those in all groups who ate at will became obese, and displayed symptoms of disease onset. Those on time-restricted diets, even with high fat and high-sucrose diets, remained healthy.

During the study, some of the obese animals were then placed on time-restricted diets.

Correspondingly, they lost weight and disease markers. Noted lead author Satchidananda Panda, “Time-restricted eating didn’t just prevent but also reversed obesity.”

LEPTIN AND AUTOIMMUNITY

We already know that there are  many hormonal factors involved in weight loss. Many autoimmune disease and thyroid patients show signs of leptin resistance and many thyroid patients with elevated leptin levels also have high Reverse T3 levels, which lowers metabolism, and makes weight loss even more difficult.

One of the key ways to help sensitize the leptin response and lower stress – and Reverse T3 -- is to space out meals, and to have a substantial “fasting time” overnight – from 8 to 12 hours. This knowledge is now being explored further in new studies into time-restricted eating.

TIME-RESTRICTED EATING - IS IT A WEIGHT-LOSS BREAKTHROUGH? 

These studies have yet to be replicated in humans, but they provide solid food for thought, and some ideas to consider in terms of your own efforts to lose weight.

• Eating at all hours of the day could be disruptive to wellness, lead to weight gain and contribute to potential disease development
• The body may need to enter periodic phases of fasting in order to best use nutrition consumed during periods of wakefulness
• Keeping eating activities within a 12-hour time period during the day could lead to better health
• If prone to eating at all hours, resuming time-restricted eating patterns could improve health

Because rates of obesity are on the rise, this kind of research is important. If human studies show similar results, it may open the door to greater understanding of the complex interaction of human metabolism, digestion, and the factors that bear on both.

RECOMMENDED RESOURCES 

To learn more about how you can implement leptin-reducing, time-restricted eating, read about intermittent fasting.

I also recommend the book, Mastering Leptin by Byron Richards.