effective strategies to tackle obesity appetite control: the...

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

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

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

Why high-protein ?

• One diet does not achieve all of this for all people, but it can be a helpful tool

• 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

Definition of high protein diets and discussion of relevance of type of protein in the diet (animal and plant sources)

• 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.

• 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)

http://www.wcrf.org/int/cancer-facts-figures/link-between-lifestyle-cancer-risk/meat-consumption-patterns

Johnstone AM. Safety and efficacy of high-protein diets for weight loss. Proc Nutr Soc. 2012 May;71(2):339-49.


• 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.

• 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.

• 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.

• 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)

http://www.wcrf.org/int/cancer-facts-figures/link-between-lifestyle-cancer-risk/meat-consumption-patterns


http://www.wcrf.org/int/research-we-fund/our-cancer-prevention-recommendations

http://www.wcrf.org/int/research-we-fund/our-cancer-prevention-recommendations

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

Effectiveness of high protein diets for appetite control and weight management (weight loss, weight maintenance after weight loss)


• Weigh up benefits of fat loss versus risk of dietary restriction

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

http://www.abdn.ac.uk/rowett/research/alex-johnstone.php

0

10

20

30

40

50

60

B0 B1 B2 B3 B4 B5 B6 L0 L1 L2 L3 L4 L5 L6 D0 D1 D2 D3

MEAT

SOYA

• 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)

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. 2014 Jun 18;100(2):548-558.

Type of protein : animal and plant sources

• 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.

Gilbert et al. Effect of proteins from different sources on body composition. Nutr Metab Cardiovasc Dis. 2011 Sep;21 Suppl 2:B16-31.

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. 2012 Sep;96(3):632-9.

FAVABEAN: 5.5g protein in 100g

HEMP: 33.3g per 100g

BUCKWHEAT:13.3g per 100g

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


Sustainable diet for the plant and our health: GHG emissions

GREEN PEA: fresh peas 6.7g protein in 100g

http://assets.wwf.org.uk/downloads/livewell_report_jan11.pdf

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. 2012 Sep;96(3):632-9.


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)

Safety of high protein diets


Bone health including osteoporosis Renal function CVD risk factors including lipaemia Gut health Antioxidant status Dieting and stress and cognitive function

• 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

• 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.

Relationship between carbohydrate intake (average over 7 days preceding donation of stool sample for moderate-

and low-carbohydrate diets; average of 3 days preceding stool sample for maintenance) and butyrate concentration

in faeces

•, maintenance diet; ×, HPMC diet; □, HPLC diet.

Duncan SH, Johnstone AM et al. Appl. Environ. Microbiol. 2007;73:1073-1078 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.

Mechanisms of protein induced satiety (psychology & physiology & behavior)

• The role of decision-making areas is not yet well understood (yet)

Journel M, Chaumontet C, Darcel N, Fromentin G, Tome D (2012) Brain responses to high-protein diets. Adv Nutr. 1;3(3):322-9.

CCK, cholecystokinin GLP-1, glucagon-like peptide 1 PYY, peptide YY

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 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, 1729-30.

Understanding food-gut-brain mechanisms across the lifespan in the regulation of hunger and satiety for health

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. 149-157.

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

Effectiveness of high protein diets for appetite control and weight management: weight maintenance after weight loss

• 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% vs. ~37%)

Larsen et al. (2010) Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance New England Journal of Medicine, 363: 2102-2113.

These data 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.

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

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)

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

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

Future application of dietary protein for weight management in food industry context

Few studies directly assess appetite in the elderly and how to deliver food to maximize nutrition and prevent sarcopenia (multi-nutritional strategy)

‘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.

Protein as a functional food – the future

Preparation of protein isolates for food industry

Targeted marketing (evidence base)

Gluten free or free from growth

Lifestyle choice – target ageing population

Research and innovation – reformulation for ‘health by stealth’ or substitution for ‘reformulation’

Identify barriers to acceptance (consumers/industry)

http://www.abdn.ac.uk/rowett/research/strategic-partnership.php

Dr Alex Johnstone, Senior Research Fellow Rowett Institute of Nutrition and Health, University of Aberdeen

Email : [email protected]

Web : http://www.abdn.ac.uk/rowett/research/alex-johnstone.php

Twitter : Dr_A_Johnstone

Thank you, Questions?

https://www.futurelearn.com/courses/nutrition-wellbeing/

SATIN http://www.satin-satiety.eu

Full4Health http://www.full4health.eu

mailto:[email protected]




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