Effective strategies to tackle obesity. Appetite control: The role of dietary protein for healthy weight management. Dr Alexandra Johnstone

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1 Effective strategies to tackle obesity Appetite control: The role of dietary protein for healthy weight management Dr Alexandra Johnstone The research leading to these results has received funding from the European Community s Seventh Framework Programme And the Scottish Government

2 Topics Definition of high protein diets and discussion of relevance of type of protein in the diet (animal and plant sources) Effectiveness of high protein diets for appetite control and weight management (weight loss, weight maintenance after weight loss) Safety of high protein diets Mechanisms of protein induced satiety (psychology & physiology & behavior) Future application of dietary protein for weight management in food industry context

3 Why high-protein? Solving the obesity epidemic requires three approaches: - prevent weight gain - promote weight loss - maintain a lower body weight It is generally accepted that diet composition strongly affects ad libitum energy intake, under laboratory and free-living conditions with protein highlighted as the most satiating macronutrient Increased protein intake during calorie deficit is beneficial for appetite control and motivation to eat : hunger a main limitation during calorie restriction In theory, weight loss is relatively easy and is achieved when EI < EE In practice, however, many dieters find this difficult to achieve or sustain One diet does not achieve all of this for all people, but it can be a helpful tool

4 Definition of high protein diets and discussion of relevance of type of protein in the diet (animal and plant sources) The protein composition of an individuals diet can be considered in different ways Grams (g), or g/kg body weight % of total energy (calories) as protein UK is ~16% of energy intake for a sedentary adult (approx 64-88g/d) High protein diets in weight loss studies ~30% of energy intake as protein Not absolute protein intake (g) is doubled, as energy intake is reduced It is still not clear exactly the amount (g or %), type of protein (vegetable, diary or animal) that is required to promote satiety required to induce or maximise protein induced satiety or whether there is a relationship with the energy density of the diet. Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc May;71(2):

5 Definition of high protein diets and discussion of relevance of type of protein in the diet (animal and plant sources) The protein composition of an individuals diet can be considered in different ways Grams (g), or g/kg body weight % of total energy (calories) as protein UK is ~16% of energy intake for a sedentary adult (approx 64-88g/d) Global patterns of meat consumption reveal trends towards increased meat consumption. Consumption of red and processed meat has been associated with an increased risk of colorectal cancer. High protein diets in weight loss studies ~30% of energy intake as protein Not absolute protein intake (g) is doubled, as energy intake is reduced It is still not clear exactly the amount (g or %), type of protein (vegetable, diary or animal) that is required to promote satiety required to induce or maximise protein induced satiety or whether there is a relationship with the energy density of the diet. WCRF & WHO recommendations for cancer prevention encourage people to limit their consumption of red meat to less than 500g a week (with emphasis on less processed meat). From systematically reviewed evidence linking diet and food intake patterns to cancer risk. Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc May;71(2):

6 Definition of high protein diets and discussion of relevance of type of protein in the diet (animal and plant sources) Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc May;71(2):

7 Effectiveness of high protein diets for appetite control and weight management (weight loss, weight maintenance after weight loss) Not a low-carbohydrate diet 30% protein 40% CHO 30% Fat Greater fat loss Retention of lean body mass Compliance adherence Palatable diet Mixed protein sources Weigh up benefits of fat loss versus risk of dietary restriction Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc May;71(2):

8 From science base to supermarket shelf Effectiveness of high protein diets for appetite control and weight management Meal requirements Protein enriched (30% protein) Moderate carbohydrates (40%) Low fat (30%) Vegetable - one serving per dish

9 Type of protein : animal and plant sources Weight loss of 2.41 and 2.27 kg on vegetarian & meat diets, respectively (p=0.356, SED 3.7) Similar appetite control (motivation to eat) Scant evidence to support/reject plant protein for appetite control Gilbert et al, (2011) reviewed protein source on body composition during weight loss, aside from the appetite effects. Animal proteins, especially those from dairy, seem to support better muscle protein synthesis during weight reduction regimes in comparison to plant proteins because they contain all essential amino acids and are generally well digested MEAT SOYA B0 B1 B2 B3 B4 B5 B6 L0 L1 L2 L3 L4 L5 L6 D0 D1 D2 D3 Gilbert et al. Effect of proteins from different sources on body composition. Nutr Metab Cardiovasc Dis Sep;21 Suppl 2:B Johnstone et al. Appetite control and biomarkers of satiety with vegetarian (soy) and meat-based high-protein diets for weight loss in obese men: a randomized crossover trial. Am J Clin Nutr Jun 18;100(2):

10 Type of protein : animal and plant sources World Cancer Research Fund (WCRF) report suggests that if people eat 50g of processed meat a day then their bowel cancer risk is increased by 20 per cent FAVABEAN: 5.5g protein in 100g GREEN PEA: fresh peas 6.7g protein in 100g HEMP: 33.3g per 100g BUCKWHEAT:13.3g per 100g Sustainable diet for the plant and our health: GHG emissions Sustainable diets for the future: can we contribute to reducing greenhouse gas emission by eating a healthy diet? Macdiarmid, Kyle, Horgan, Loe, Fyfe, Johnstone, McNeill. Am J Clin Nutr Sep;96(3):632-9.

11 Type of protein : animal and plant sources Sustainability of protein source Current global meat consumption impacts on the environment, and yet consumption is rising in many developing nations. As much as 32 per cent of greenhouse gas emissions come from rearing livestock, a third of the world's cultivated land is used to grow animal feed, and it takes 15,500 (a small swimming pool) to produce 1kg of beef Eat less meat but better Alternative, sustainable sources of protein for farm (animal feed) to fork (human food) Muscle development (Muscle hypertrophy) Just increasing protein intake will not increase muscularity! General rule for adults - more than 30 g protein in a single meal does not further enhance the stimulation of muscle protein synthesis in young and elderly Irrespective of source, meals should contain a moderate amount of high-quality protein (slight differences in digestability and bio-availability of protein rich foods) Sustainable diets for the future: can we contribute to reducing greenhouse gas emission by eating a healthy diet? Macdiarmid, Kyle, Horgan, Loe, Fyfe, Johnstone, McNeill. Am J Clin Nutr Sep;96(3):632-9.

12 Safety of high protein diets Both the safety and efficacy (St Jeor et al, 2001) of high-protein weight loss diets have been questioned, particularly in combination with low-carbohydrate advice (Astrup, 2005). This has been recently reviewed (Johnstone, 2012) with growing evidence to support the use of high-protein, moderate-carbohydrate diets as a dietary tool to achieve weight loss Bone health including osteoporosis Renal function CVD risk factors including lipaemia Gut health Antioxidant status Dieting and stress and cognitive function Possible kidney damage due to high levels of nitrogen excretion during protein metabolism, which can cause an increase in glomerular pressure and hyperfiltration. Meta-analyses and human studies, propose that even high levels of protein in the diet do not damage renal function. In subjects with intact renal function, higher dietary protein levels caused some functional and morphological adaptations without negative effects. Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc May;71(2):

13 Relationship between carbohydrate intake (average over 7 days preceding donation of stool sample for moderateand low-carbohydrate diets; average of 3 days preceding stool sample for maintenance) and butyrate concentration in faeces, maintenance diet;, HPMC diet;, HPLC diet. Low CHO intakes give lower faecal butyrate concentrations: negative long term impact on colonic health. Inappropriate long-term use of low CHO diets may compromise gut health. Duncan SH, Johnstone AM et al. Appl. Environ. Microbiol. 2007;73:

14 Mechanisms of protein induced satiety (psychology & physiology & behavior) Journel M, Chaumontet C, Darcel N, Fromentin G, Tome D (2012) Brain responses to high-protein diets. Adv Nutr. 1;3(3): Mechanisms responsible for the protein induced reduction in food intake Protein intake leads to the production of specific hormones that reach the brain via the vagus nerve or bloodstream Role of increased satiety and protein ingestion to decrease the motivation to eat in the mesolimbic reward system The role of decision-making areas is not yet well understood (yet) CCK, cholecystokinin GLP-1, glucagon-like peptide 1 PYY, peptide YY

15 The physiological processes of appetite control of protein-rich diets during negative energy balance is not clearly understood. Possible mechanisms:- Protein slows the rate of passage through the small intestine, physical sense of fullness Physical structure (solid vs liquid), energy density, volume and protein type-content on ad libitum food intake Protein stimulates the release of gut hormones (e.g. peptide YY), which promote the feeling of fullness or reduces feeling of hunger Different feeding routes, including intravenous feeding and/or nasogastric feeding can help elucidate the potential feedback from the stomach and brain; measuring gut hormones; how much protein (threshold amount) and what structure? Role of the liver in metabolite production from amino acids, which can be linked via the vagal nerve, to the brain s sense of hunger Measurement and manipulation of plasma amino acid profile will help understand the role of these within the context of circulating metabolite interactions. Thus, is rate of delivery of amino acids important? Direct action of amino acids in the brain, entering via across the blood brain barrier Use of brain imaging tools to assess nutrient profile on motivation to eat. Assessing brain responses to feeding will further elucidate the role of physiology and learning Johnstone (2009) British Journal of Nutrition, 101,

16 Understanding food-gut-brain mechanisms across the lifespan in the regulation of hunger and satiety for health Eating is a form of behaviour and should be rewarding and provide nutrients for health Ageing poor appetite how to eat enough protein? Health ageing a high potential market for function foods Mercer, JG., Johnstone, A. & Halford, JCG. (2015). 'Approaches to influencing food choice across the age groups: from children to the elderly'. Proceedings of the Nutrition Society, vol 74, no. 02, pp

17 Effectiveness of high protein diets for appetite control and weight management: weight maintenance after weight loss Larsen et al. (2010) Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance New England Journal of Medicine, 363: Weight regain was 0.93 kg less for participants on a high protein diet than for those on a low protein diet. Fewer participants in the high-protein, low-gi groups dropped out of the project than in the low protein. (~26% These data vs. ~37%) provide some support the use of high-protein, moderate carbohydrate diets to achieve weight control. By (i) favouring regain of fat free mass at the cost of fat mass at a similar physical activity level, (ii) reducing energy efficiency with respect to the body mass regained, and (iii) increasing satiety.

18 Future application of dietary protein for weight management in food industry context Working alongside the food/drinks industry, food scientists and food manufacturers can develop plant sources of protein can be effectively utilised as part of a healthy but sustainable diet Protein remains a promising dietary tool to control appetite during weight loss: Type of protein less important than amount (g/kcal or %) Elevated levels of dietary protein during energy restriction is effective for satiety & satiation in combination with carbohydrate Reproducible results over longer term required, especially for type of protein (plant) It is unlikely that the population will turn to a complete vegetarian diet, but substitution of alternative (non-meat) sources of protein may be a sustainable route for consumers Future research for macronutrients for appetite control: Use of protein/cho in weight maintenance ( & post weight loss) Role of protein (plant) for sarcopenia in ageing population Obesity management and snack foods in the workplace Gut microbiota role in satiety role of food matrix

19 Protein as a functional food the future Research and innovation reformulation for health by stealth or substitution for reformulation Preparation of protein isolates for food industry Targeted marketing (evidence base) Gluten free or free from growth Lifestyle choice target ageing population One diet approach does not fit all people - public health advice and food strategies need to be tailored for specific phenotypes to generate a sustainable & healthy approach for appetite control. Identify barriers to acceptance (consumers/industry) Few studies directly assess appetite in the elderly and how to deliver food to maximize nutrition and prevent sarcopenia (multi-nutritional strategy)

20 Thank you, Questions? SATIN ategic-partnership.php Full4Health Dr Alex Johnstone, Senior Research Fellow Rowett Institute of Nutrition and Health, University of Aberdeen Alex.Johnstone@abdn.ac.uk Web : Twitter : Dr_A_Johnstone