Does The Timing Of Your Meals Affect Weight Loss? Your Genes May Have The Answer

By Dr. Robyn Murphy, ND and Uroj Mohsin, BSc.

Trying to lose weight can be a stressful and challenging process. Most people turn to dietary solutions to achieve their goals or focus on exercising at the gym. Some individuals are successful when following these interventions but around 20% of overweight individuals struggle to lose more than 10% of their initial body weight. After losing weight, many still struggle to maintain that weight loss. In addition to caloric consumption and expenditure – the timing of meals can make a big difference in how much weight is lost.

Your inner circadian cycle is responsible for many of your physiological and bodily functions. This clock explains why you have a sleep-wake cycle. Similarly, you also have an energy metabolism cycle, which maintains food intake and eating habits. This rhythm works together with energy regulation, metabolism and fat digestion. The disruption of this cycle by changing timings of meals can be a cause for difficulty in weight loss.

The PER2 gene is a circadian clock gene that encodes the PER2 protein, which helps to regulate your daily rhythm of activity, metabolism and behaviour. Variations in the PER2 gene can lead to increased risk for obesity, metabolic syndrome, changes in lipid concentrations and changes in glucose metabolism. Most importantly, variations in this gene can disrupt the internal molecular clock leading to more difficulty losing weight when eating lunch later in the day. Interestingly, studies show that in those with a particular genotype, eating lunch after 3:00pm decreases the effectiveness of weight loss and may even promote weight gain.


“Variations in the PER2 gene can lead to increased risk for obesity, metabolic syndrome, changes in lipid concentrations and changes in glucose metabolism.”

Another gene, PLIN1, encodes the protein perilipin, which regulates lipid storage and breakdown in adipocytes. The circadian rhythm regulates metabolism and energy homeostasis in peripheral tissues, including adipocytes. In the ONTIME study (n=1287) obese individuals with the AA genotype, had a decrease in weight-loss effectiveness when they ate lunch late vs the TT genotypes, who saw no difference in weight loss according to their timing of meals, despite eating the same amount of food.

Consequences of having these genetic variations:

  • Increased likelihood of being an extreme snacker
  • Experience stress with dieting
  • Increased likelihood to eat when bored or skip breakfast
  • Decreased dedication to weight loss programs and meeting weight loss goals

Some helpful suggestions to modify the gene expression:

  • Eat three meals at regular times throughout the day. Eat lunch ideally before 3pm to enhance weight loss.
  • Try a supervised weight loss program from a healthcare practitioner or dietitian/nutritionist for individualized support, behavioural modification techniques, and accountability that will help you reach your goal.
  • Aerobic exercise will also likely help you with weight loss. The Canadian physical activity guidelines recommend 150 minutes per week of moderate to vigorous intensity aerobic physical activity, in periods of 10 minutes or more.

The success of weight loss strategies depends not only on appropriate dietary, exercise, and nutritional interventions, but behavioural components such as timing of meals. Genetic testing is an easy way to modify both nutritional and behavioural weight loss strategies appropriate for you.



  1. A Garcia-Rios et al. A Period 2 Genetic Variant Interacts with Plasma SFA to Modify Plasma Lipid Concentrations in Adults with Metabolic Syndrome, The Journal of Nutrition, Volume 142, Issue 7, July 2012, Pages 1213–1218,
  2. Englund, A., et al. 2009. NPAS2 and PER2 are linked to risk factors of the metabolic syndrome. Journal of Circadian Rhythms, 7, p.Art. 5. DOI:
  3. M Garaulet et al. Lunch eating predicts weight-loss effectiveness in carriers of the common allele at PERILIPIN1: the ONTIME (Obesity, Nutrigenetics, Timing, Mediterranean) study, The American Journal of Clinical Nutrition, Volume 104, Issue 4, October 2016, Pages 1160–1166,
  4. Wing RR, Phelan S. Long-term weight loss maintenance. Am J Clin Nutr. 2005 Jul;82(1 Suppl):222S-225S. doi: 10.1093/ajcn/82.1.222S. PMID: 16002825.


Dr. Robyn Murphy, ND
Scientific Advisory Board Member