Obesity research group - Department of Clinical and Molecular Medicine
The exact reasons for weight regain are not completely understood. The leading hypothesis has been that it is driven by compensatory responses activated by weight loss (increased drive to eat and reduced total energy expenditure) – “Compensatory theory”.
We have recently shown that the increase in hunger feelings and ghrelin secretion, and the reduction in energy expenditure observed with weight loss are not predictors of weight regain (Nymo et al, 2019) and in fact reflect a normalization towards a lower body weight and fat mass (DeBenedictis et al, 2020).
Our research group has shown, using two different datasets from Norway and USA, that metabolic adaptation (a reduction in energy expenditure below predicted levels) in response to weight loss is modulated by energy balance and that if measurements are performed under conditions of weight stability, metabolic adaptation is minimal and, more importantly, not a predictor of weight regain in the long-term (Martins et al, 2020).
We have, therefore, proposed that the increase in the drive to eat and the reduction in energy expenditure, which accompany weight loss, represent a normalization towards a lower body weight – Normalization theory. This represents a major paradigm shift in our understanding of relapse in obesity management.
Impact of weight loss induced by diet versus bariatric surgery on appetite and gut microbiota
Marthe Aukan, PhD candidate
The reasons for the success of bariatric surgery, in achieving long-term weight loss maintenance, remain to be fully understood. We are now comparing how the same weight loss induced by bariatric surgery (RYGB and sleeve gastrectomy) versus diet impact on appetite (homeostatic and hedonics systems) and gut microbiota and if earlier changes can predict long-term outcomes.
Suboptimal weight loss after RYGB
Siren Nymo, PhD Candidate
Approximately 15% of the patients experience suboptimal weight loss after RYGB and the exact reasons for this remain unknown. We are now investigating potential mechanisms associated with suboptimal weight loss 10 years after RYGB. Areas of interest include the homeostaic and hedonic appetite control systems, food intake, eating behavior and gut microbiota.
* Roux-en-Y Gastric Bypass (RYGB)
Carbohydrate intake, ketosis and appetite suppression during weight loss
Jessica Røekenes, PhD Candidate
Our research group has shown that being in ketosis prevents the increase in hunger feelings and ghrelin secretion otherwise seen with weight loss (Nymo et al, 2017; Lyngstad et al, 2019). Our research group is now trying to identify the maximum threshold of carbohydrate intake still associated with ketosis and appetite suppression (no increase in hunger feelings or ghrelin secretion) in low-energy diets.
Efficacy, feasibility and safety of ketogenic diets in preventing relapse
Silvia Coutinho, Postdoc
We are at present evaluating the feasibility, efficacy and safety of a low-carbohydrate ketogenic diet for the maintenance of weight loss in the long-term, as a treatment option in obesity management.
We are interested in nutritional and dietary factors, such as energy intake, macronutrient distribution, intake of different food groups and meal patterns, as well as diet-induced thermogenesis, in relation to body weight homeostasis in patients with obesity.
We are investigating the dietary factors related to risk variants of the FTO gene in patients with severe obesity. The intake of food groups has also been investigated epidemiologically in the HUNT3 study in relation to central obesity, and also the gene-environment interaction effects of FTO, MC4R and lifestyle factors on obesity has been assessed using an extreme phenotype sampling design.
In addition we will study how dietary factors are effecting non-communicable diseases (also those beyond obesity) using HUNT data. In collaboration with the Nutrition Committee of St. Olavs hospital, we are also assessing the hospital meals qualitatively and quantitatively and its potential association with risk of malnutrition.
Project leader: Ingrid Løvold Mostad
- Martins C, Nymo S, Truby H, Rehfeld JF, Hunter GR, Gower BA. Association Between Ketosis and Changes in Appetite Markers with Weight Loss Following a Very Low-Energy Diet. Obesity. 2020;28(12):2331-8.
- Deemer SE, Plaisance EP, Martins C. Impact of ketosis on appetite regulation-a review. Nutr Res. 2020;77:1-11.
- Martins C, Dutton GR, Hunter GR, Gower BA. Revisiting the Compensatory Theory as an explanatory model for relapse in obesity management. The American Journal of Clinical Nutrition. 2020;112(5):1170-9.
- DeBenedictis JN, Nymo S, Ollestad KH, Boyesen GA, Rehfeld JF, Holst JJ, et al. Changes in the homeostatic appetite system after weight loss reflect a normalization towards a lower body weight. J Clin Endocrinol Metab. 2020;105(7):dgaa202.
- Martins C, Gower BA, Hill JO, Hunter GR. Metabolic adaptation is not a major barrier to weight loss maintenance. Am J Clin Nutr. 2020 112(3):558-65.
- Martins C, Gower BA, Hunter GR. Baseline Metabolic Variables Do Not Predict Weight Regain in Premenopausal Women. Obesity (Silver Spring). 2020;28(5):902-6.
- Martins C, Roekenes J, Salamati S, Gower BA, Hunter GR. Metabolic adaptation is an illusion, only present when participants are in negative energy balance. Am J Clin Nutr. 2020;112(5):1212-8.
- Truby H, Bennett C, Martins C. A review of the short- and long-term impact of weight loss on appetite in youth: what do we know and where to from here? Proc Nutr Soc. 2020:1-10.
The Obesity research group has a close collaboration with Obesity outpatient clinic and Centre of obesity and the Regionalt senter for fedmeforskning og innovasjon (ObeCe) at St. Olavs hospital.