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The Metabolic Health Retreat – Evidence Base

The Combe Grove Metabolic Health Retreat is based on our Five Roots of Metabolic Health: Nutrition, Movement, Sleep, Mindset and Environment. At each stage of the Programme development, our experienced Team has considered the latest science to develop these five roots and produce evidence-based recommendations to help our guests achieve positive lifestyle changes with the potential to prevent the onset of diabetes and potentially reverse prediabetes.

A list of peer-reviewed journal articles underpinning the Metabolic Health Retreat can be found below:


Evidence for outlining why we support a low-carb diet  

Brown, A., McArdle, P., Taplin, J., Unwin, D., Unwin, J., Deakin, T., … & Mellor., D. (2020). Dietary strategies for remission of type 2 diabetes: A narrative.


  • Narrative review supporting the use of a low-carb diet to achieve remission from Type 2 diabetes.


Feinman, R. D., Pogozelski, W. K., Astrup, A., Bernstein, R. K., Fine, E. J., Westman, E. C., … & Worm, (2015). Dietary carbohydrate restriction as the first approach in diabetes management: critical review and evidence base. Nutrition, 31, 1-13.


  • A review paper highlights that a restricted-carb diet is an effective means of managing high blood sugar and Type 2 diabetes.
  • The review also defines a ‘low-carb’ diet as 130g of carbohydrate per day or less. This is what we are working on at Combe Grove. There has previously been no consensus on the definition of ‘low-carb’.


Hussain, T. A., Mathew, T. C., Dashti, A. A., Asfar, S., Al-Zaid, N., & Dashti, H. M. (2012). Effect of low calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition, 28, 1016



  • Evidence that a low-carbohydrate diet is effective in promoting weight loss and reducing blood sugar over 24 weeks.


Centers for Disease Control and Prevention. (2004). Trends in intake of energy and macronutrients United States: 1971 to 2000, JAMA, 291, 1193-1194.


  • The study followed 5000 Americans from 1974 to 2000.
  • Evidence that the increase in Type 2 diabetes is linked to an increase in carbohydrates in the Western diet, and not an increase in fat. Suggest that reducing carbs in our diet may therefore help to tackle rising diabetes cases.


Westman, E. C., Yancy, W. S., Mavropoulos, J. C., Marquart, M., & McDuffie, J. R. (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & metabolism, 5, 1-9.


  • Evidence that a low-carb diet is an effective tool for achieving weight loss and a reduction in HbA1c, a measure of the average sugar content of the blood over 12 weeks. More effective than a low-calorie diet.


Evidence outlining why we recommend a protein source at each meal


Krieger, J. W., Sitren, H. S., Daniels, M. J., & Langkamp-Henken, B. (2006). Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. The American journal of clinical nutrition, 83(2), 260-274.


  • Evidence that a high protein diet helps to prevent loss of lean tissue (muscle mass) when following a low carb diet. Sustaining adequate muscle mass is important for protecting against Type 2 diabetes, especially as we get older.


Phillips, S. M., Paddon-Jones, D., & Layman, D. K. (2020). Optimizing adult protein intake during catabolic health conditions. Advances in Nutrition, 11, 1058-1069.


  • Review outlining the benefits of higher protein diets for optimising health during ageing, inactivity, bed rest, or metabolic dysfunction such as type 2 diabetes.


Areta, J. L., Burke, L. M., Ross, M. L., Camera, D. M., West, D. W., Broad, E. M., … & Coffey, V. G. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. The Journal of Physiology, 591, 2319-2331.


  • Evidence that protein ingestion is most effective at stimulating muscle protein synthesis when a moderate amount of protein is consumed at every meal.


Evidence that protein increases satiety and may reduce caloric intake

Bowen J, Noakes M, Trenerry C, Clifton PM 2006 Energy intake, ghrelin and cholecystokinin after

different carbohydrate and protein preloads in overweight men. Journal of Clinical

Endocrinology and Metabolism, 91, 1477–1483.


  • The study showed that consuming a protein-rich beverage before a meal led to reduced appetite and reduced calorie consumption when compared to a glucose-rich beverage.


Foster-Schubert, K. E., Overduin, J., Prudom, C. E., Liu, J., Callahan, H. S., Gaylinn, B. D., Thorner, M.

O., & Cummings, D. E. (2008). Acyl and total ghrelin are suppressed strongly by ingested

proteins, weakly by lipids, and biphasically by carbohydrates. The Journal of Clinical

Endocrinology and Metabolism, 93, 1971–1979.


  • Study shows that a protein-rich drink effectively suppresses the hunger hormone ghrelin over six hours, whereas a carbohydrate-rich drink suppresses ghrelin for three hours followed by a marked overshoot above baseline.



Evidence outlining why we support the inclusion of natural fats in our diet and do not support a low-fat diet:


Howard, B. V., Van Horn, L., Hsia, J., Manson, J. E., Stefanick, M. L., Wassertheil-Smoller, S., and Kotchen, J. M. (2006). Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 295, 655-666.


  • Study of 48,000 post-menopausal women
  • Evidence that a low-fat diet does not reduce the risk of coronary heart disease, and cardiovascular disease, which are risk factors for Type 2 diabetes.


Deakin, T., & Garden, L. (2015). Saturated fat doesn’t increase coronary heart disease in people with diabetes. Practical Diabetes, 32, 254-260.


  • A review of studies considers the relationship between saturated fat in the diet, such as that found in animal products such as meat and dairy, and the risk of coronary heart disease. Concluded that saturated fat in the diet does not increase the risk of CHD.


Siri-Tarino, P. W., Sun, Q., Hu, F. B., & Krauss, R. M. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition, 91(3), 535-546.


  • During 5–23 y of follow-up of 350,000 subjects, 11,000 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD.



Evidence that ingestion of foods rich in fats may slow the rate of release of glucose into the blood

Jenkins, D. J., Kendall, C. W., Josse, A. R., Salvatore, S., Brighenti, F., Augustin, L. S., … & Rao, A. V.

(2006). Almonds decrease postprandial glycemia, insulinemia, and oxidative damage in

healthy individuals. The Journal of Nutrition, 136, 2987-2992.


  • Studies show that eating raw, unblanched almonds, a source of fat, with white bread increases satiety scores compared to eating white bread alone.
  • Peak post-prandial blood glucose levels were significantly lower following a meal of almonds and white bread than a meal of white bread alone.


Lilly, L. N., Heiss, C. J., Maragoudakis, S. F., Braden, K. L., & Smith, S. E. (2019). The effect of added

peanut butter on the glycemic response to a high–Glycemic index meal: A pilot study.

Journal of the American College of Nutrition, 38, 351-357.


  • Study shows that adding two tablespoons of peanut butter, a source of fat, to a meal of white bread and apple juice (high carb meal) significantly attenuated the magnitude of blood glucose spikes and overall glycaemic response compared with the high carb meal alone.


Shukla, A. P., Dickison, M., Coughlin, N., Karan, A., Mauer, E., Truong, W., … & Aronne, L. J. (2019).

The impact of food order on postprandial glycaemic excursions in prediabetes. Diabetes,

Obesity and Metabolism, 21, 377-381.


  • Studies show that, in a prediabetic population, eating protein and vegetables before carbohydrate confers a significant reduction in postprandial glycaemia compared with eating carbohydrates before protein and vegetables.
  • Effects were largely put down to the effect of fat and fibre content of meals, however.


Crouch, M. A., & Slater, R. T. (2016). Almond “appetizer” effect on glucose tolerance test (GTT)

results. The Journal of the American Board of Family Medicine, 29, 759-766.


  • Studies show that, in a prediabetic population, eating almonds 30 mins before an oral glucose tolerance test reduces postprandial glycaemia. This was actually attributed to fibre and fat content.



Evidence outlining why we recommend intake of non-starchy vegetables, broccoli, cauliflower, asparagus etc, as the largest component of any given meal


Martin, K. E. (2017). Glycaemic response to varying the proportions of starchy foods and non-starchy vegetables within a meal: A randomised controlled trial (Doctoral dissertation, University of Otago).


  • Evidence that meals with larger proportions of starchy carbs, pasta/rice, and smaller portions of non-starchy vegetables cause the greatest increase in blood sugar levels. Meals that contain smaller proportions of starchy carbs and larger proportions of non-starchy vegetables have the lowest impact on blood sugar.


Moore, L. L., Singer, M. R., Bradlee, M. L., & Daniels, S. R. (2016). Adolescent dietary intakes predict cardiometabolic risk clustering. European Journal of Nutrition, 55, 461-468.


  • Evidence that eating plenty of non-starchy vegetables earlier in life may have a protective effect against risk factors for Type 2 diabetes and cardiovascular disease



Evidence that eating a diverse, plant-rich diet is associated with a healthy and diverse microbiome

Van der Merwe, M. (2021). Gut microbiome changes induced by a diet rich in fruits and vegetables.

International Journal of Food Sciences and Nutrition, 72, 665-669.


  • Review paper outlining the evidence for a link between habitual intake of diverse fruit and veg and increased microbial diversity within the gut, with possible implications for reduced chronic disease.


Evidence that eating plenty of non-starchy vegetables is associated with reduced inflammation within the body

Menni, C., Louca, P., Berry, S. E., Vijay, A., Astbury, S., Leeming, E. R., … & Valdes, A. M. (2021). High

intake of vegetables is linked to lower white blood cell profile and the effect is mediated by

the gut microbiome. BMC Medicine, 19, 1-10.


  • Studies show that a habitual diet high in vegetables, but not fruits, is linked to a lower inflammatory profile for white blood cells, and a fifth of the effect is mediated by the effects of vegetable intake on the gut microbiome.

Evidence that eating a diverse, plant-rich diet is associated with a healthy and diverse microbiome

van der Merwe, M. (2021). Gut microbiome changes induced by a diet rich in fruits and vegetables.

International Journal of Food Sciences and Nutrition, 72, 665-669.


  • Review paper outlining the evidence for a link between habitual intake of diverse fruit and veg and increased microbial diversity within the gut, with possible implications for reduced chronic disease.



Evidence underpinning our commitment to drinking plenty of water and minimising sugar-sweetened beverages and artificially sweetened beverages

Armstrong, L. E., Barquera, S., Duhamel, J. F., Hardinsyah, R., Haslam, D., & Lafontan, M. (2012).Recommendations for healthier hydration: addressing the public health issues of obesity and type 2 diabetes. Clinical Obesity, 2, 115-124.


  • A consensus statement from experts in medicine, nutrition, physiology and public health on healthy hydration practices tackling obesity and Type 2 diabetes.



Evidence that non-alcoholic drinks contain more sugar and are more highly processed


Bauwens, J., Van Opstaele, F., Eggermont, L., Weiland, F., Jaskula?Goiris, B., De Rouck, G., … & De

Cooman, L. (2021). Comprehensive analytical and sensory profiling of non-alcoholic beers

and their pale lager beer counterparts. Journal of the Institute of Brewing, 127, 385-405.


  • Comprehensive analytical and sensory evaluation of pale lager beers and their non—alcoholic counterparts.
  • Non-alcoholic beers clearly differ in that they typically contain higher levels of carbohydrates, lower amounts of esters and higher alcohols, different amino acid profiles and higher levels of aldehyde markers.



Evidence underpinning our commitment to time-restricted eating


Wilkinson, M. J., Manoogian, E. N., Zadourian, A., Lo, H., Fakhouri, S., Shoghi, A., … & Taub, P. R. (2020). Ten-hour time-restricted eating reduces weight, blood pressure, and atherogenic lipids in patients with metabolic syndrome. Cell Metabolism, 31, 92-104.


  • Evidence that TRE (10-hr eating window) reduces risk factors for Type 2 diabetes including waist circumference, percent body fat, visceral fat, blood pressure, HbA1c, a measure of blood sugar


Cienfuegos, S., McStay, M., Gabel, K., & Varady, K. A. (2022). Time-restricted eating for the prevention of type 2 diabetes. The Journal of Physiology, 600, 1253-1264.


  • Review outlining the evidence for the effectiveness of TRE on body weight and markers of glycaemic control, both risk factors for Type 2 diabetes

Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metabolism, 27, 1212-1221.


  • Evidence that TRE can reduce risk factors for Type 2 diabetes, insulin resistance, high blood pressure, and oxidative stress, in individuals with prediabetes.




National guidelines support regular participation in diverse physical activities to reduce the risk of disease

Department of Health. (2019). UK Chief Medical Officers Physical Activity Guidelines. London:

Department of Health.


  • This report presents an update to the 2011 physical activity guidelines issued by the four Chief Medical Officers (CMOs) of England, Scotland, Wales and Northern Ireland.
  • The UK CMOs draw upon global evidence to present guidelines for different age groups, covering the volume, duration, frequency and type of physical activity required across the life course to achieve health benefits.


Evidence in support of a protective effect of regular aerobic and resistance activity on metabolic health    

Smith, A. D., Crippa, A., Woodcock, J., & Brage, S. (2016). Physical activity and incident type 2

diabetes mellitus: A systematic review and dose–response meta-analysis of prospective cohort

studies. Diabetologia, 59, 2527-2545.


  • A systematic review considering the relationship between physical activity and incidence of type 2 diabetes.
  • The review concluded a risk reduction of 26% for type 2 diabetes among those who achieved equivalent to 150 min/week of moderate activity relative to inactive individuals.


Colberg, S. R., Sigal, R. J., Fernhall, B., Regensteiner, J. G., Blissmer, B. J., Rubin, R. R., … & Braun, B.

(2010). Exercise and type 2 diabetes: The American College of Sports Medicine and the American

Diabetes Association: Joint position statement. Diabetes Care, 33, 147-167.


  • A position statement from the American College of Sports Medicine and the Americal Diabetes Association outlining the benefits of undertaking regular muscle strengthening and aerobic activities, including improved insulin action, blood glucose control, and fat oxidation, all of which are critical in the prevention and treatment of type 2 diabetes and metabolic syndrome.


Evidence outlining the links between sedentary behaviour and risk of cardiometabolic disease and mortality

Patterson, R., McNamara, E., Tainio, M., de Sá, T. H., Smith, A. D., Sharp, S. J., … & Wijndaele, K.

(2018). Sedentary behaviour and risk of all-cause, cardiovascular and cancer mortality, and

incident type 2 diabetes: A systematic review and dose response meta-analysis. European

journal of epidemiology, 33, 811-829.


  • A systematic review considering the relationship between sedentary behaviour, such as TV watching, and the risk of cardiometabolic disease and mortality.
  • The review concluded that sedentary behaviour was linked with an increased risk of cardiometabolic disease and mortality, with the strongest association being between TV viewing and incident of type 2 diabetes.



Evidence that sleep deprivation impacts negatively on metabolic health

Al-Rashed, F., Sindhu, S., Al Madhoun, A., Alghaith, A., Azim, R., Al-Mulla, F., & Ahmad, R. (2021).

Short sleep duration and its association with obesity and other metabolic risk factors in

Kuwaiti urban adults. Nature and Science of Sleep, 13, 1225.


  • A study investigating the link between sleep duration and quality on obesity and cardiometabolic risk factors.
  • The study concluded that reduced sleep duration and sleep quality correlate with an increase in metabolic risk factors including blood pressure, triglycerides, total cholesterol, and insulin resistance.


Evidence that shorter sleep duration is linked with poor dietary choices and sedentary behaviour

Bel, S., Michels, N., De Vriendt, T., Patterson, E., Cuenca-García, M., Diethelm, K., … & Huybrechts, I.

(2013). Association between self-reported sleep duration and dietary quality in European

adolescents. British Journal of Nutrition, 110, 949-959.


  • Studies show that fast food and soft drinks were more often consumed by adolescents ‘short sleepers’ – those who slept for an insufficient period of time (< 8hrs per night)


Garaulet, M., Ortega, F. B., Ruiz, J. R., Rey-López, J. P., Béghin, L., Manios, Y., … & Moreno, L. A.

(2011). Short sleep duration is associated with increased obesity markers in European

adolescents: effect of physical activity and dietary habits. The HELENA study. International

Journal of Obesity, 35, 13081317.


  • Studies show that adolescents who slept less than 8 hours per day were more sedentary and spent more time watching TV.
  • ‘Shorter sleepers’ tended to eat less fruit, vegetables and fish than those who slept 8 hours per day.



Evidence that a solution-focused approach may enable greater success in achieving lifestyle change 

Unwin, D., & Unwin, D. (2019). A simple model to find patient hope for positive lifestyle changes:

GRIN. Journal of Holistic Health, 16, 18-22.


  • Article outlining a simple solution-focused model for inspiring hope and facilitating lifestyle change.


Iveson, C. (2002). Solution-focused brief therapy. Advances in Psychiatric Treatment, 8, 149-156.


  • Article outlining solution-focused therapy as an approach to behavioural change based on solution-building rather than problem-solving.
  • Focusing on current resources and future hopes rather than present problems and past causes may enhance success in achieving health goals


Evidence that a positive and hopeful mindset can have a positive effect on happiness, longevity and adjustment

Unwin, J., Kacperek, L., & Clarke, C. (2009). A prospective study of positive adjustment to lower limb

amputation. Clinical Rehabilitation, 23, 1044-1050.


  • Studies show that a higher-hope mindset at the beginning of rehabilitation was related to an increase in a positive mood and general adjustment to lower limb amputation.


Diener, E., & Chan, M. Y. (2011). Happy people live longer: Subjective well-being contributes to

health and longevity. Applied Psychology: Health and Well?Being, 3, 1-43.


  • A review of seven types of evidence concludes that people who experience positive emotions such as optimism are more likely to live longer and experience better health.



Hunter, M. R., Gillespie, B. W., & Chen, S. Y. P. (2019). Urban nature experiences reduce stress in the

context of daily life based on salivary biomarkers. Frontiers in Psychology, 10, 722.


  • Field study investigating the link between spending time in nature and stress levels
  • Spending 20-30 minutes with nature produced a significant drop in the stress hormone cortisol


Oh, B., Lee, K. J., Zaslawski, C., Yeung, A., Rosenthal, D., Larkey, L., & Back, M. (2017). Health and

well-being benefits of spending time in forests: Systematic review. Environmental Health

and Preventive Medicine, 22, 1-11.


  • A systematic review found promising therapeutic benefits of forest exposure on several physical and psychological conditions including hypertension, cardiac and pulmonary function, immune function, inflammation, oxidative stress, stress, stress hormone, anxiety, depression, and emotional response.


Capaldi, C. A., Dopko, R. L., & Zelenski, J. M. (2014). The relationship between nature connectedness

and happiness: A meta-analysis. Frontiers in Psychology, 976.


  • Meta-analysis of studies reported that a greater feeling of connectedness to nature was associated with increased vitality, positive feelings and life satisfaction.