The link between circadian rhythm and weight loss.

ScalesSimply put, the circadian rhythm is the cycle that regulates our sleeping and wakefulness. However, this is a very limited description, as the circadian rhythm regulates so much more. In particular, it plays a regulatory role in fat metabolism during periods of fasting and therefore, weight loss.

The circadian rhythm is controlled by the suprachiasmatic nuclei (or SCN), a specialized area found in the hypothalamus. It takes information on the lengths of the day and night from the retina, interprets it, and passes it on to the pineal gland. In response, the pineal gland secretes the hormone melatonin. Secretion of melatonin peaks at night and ebbs during the day.

So how does this relate to weight loss?

Research has shown that in the absence of an appropriate (or irregular) circadian rhythm, the cells in the human body lose their ability to switch to fat burning mode during periods of fasting (like when we sleep at night).

Studies have found that insufficient sleep leads to weight gain, partially because there is more time available to access food and partially because the satiety hormones get thrown out of balance. Research shows that having less than 5 hours sleep a night results in lower levels of leptin (a satiety hormone) and higher levels of ghrelin (the hormone that creates hunger). Increased food intake as a result of insufficient sleep is a physiological adaptation to provide the energy needed to sustain longer hours of wakefulness; yet when food is easily accessible, intake surpasses that required.

A recent study highlighted that shift workers who suffer sleep disorders have a higher risk of becoming obese.[1] Researchers found that transitioning from an insufficient to adequate sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to weight loss.[2]

Avoiding sleep pattern disturbance is important for everyone. The circadian rhythm functions best when we go to bed at a reasonable hour and wake earlier.

There are some simple things we can do to regulate sleeping patterns.

  •       Planning a wind down time before going to bed is often a good idea
  •       Turn of the TV, mobile phone and other electronic devices.
  •       Have a relaxing bath with some essential oils.
  •       Have a soothing cup of tea – chamomile tea is a good choice.
  •       Make sure the bedroom is dark and not too warm or cold.
  •       Try meditation, to clear your mind.
  •       Have a set time when you go to bed each night, but make sure it’s not too late.

A new study recently found that a group of subjects sent out on a week-long camping trip, with exposure to only natural light and firelight, regained their natural biological rhythm within that same week (ie. their sleep-wake cycle was governed by sunrise and sunset)

Getting enough sleep (8-8.5 hours each night for adults) is surely one of the best things to aid health and keep the metabolism running well. There are various herbal remedies that can be of great use for those suffering from insomnia, or wanting to regulate their sleeping patterns. Please feel free to talk to us at your next consultation if you would like more information.


[1] Herichova, I. Changes of Physiological Functions Induced by Shift Work. Endocr Regul. 2013 Jul;47(3):159-70

[2] Markwald, R.R. Impact of Insufficient Sleep on Total Daily Energy Expenditure, Food Intake & Weight Gain. Proc Natl Acad Sci U S A. 2013 Apr 2;110(14

[3] Wright, K.P. Entrainment of the human circadian clock to the natural light-dark cycle. Curr Biol. 2013 Aug 19;23(16):1554-8