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Low carb diets – a balanced approachWhat are they?When are they not appropriate?

30th January 2019 Peterborough6th February 2019 Cambridge

Mary HallAdvanced Diabetes DietitianMary.Hall@cpft.nhs.uk

Low carbohydrate diets

• What is a low carb diet?• What are the benefits?• What are the drawbacks?• Current guidance• What should be advised?• When not to advise a low carb diet• Case Study

Introduction• Low carb diets popular in the media and growing

interest in their use for the management of T2 diabetes

• The Low Carb Program, Dr David Unwins, is now available on NHS Apps library

• Range from maximum 130g carbs to very low carb/ketogenic of 20-50g carbs per day

• However many mixed messages and patients sometimes being advised inappropriately to go low carb

• There is a need for more individualised advice

What are carbs?• Carbohydrate breaks down to glucose in blood

• Milk, yoghurt, ice cream• Fruit• 1 tsp sugar = 5g carbohydrate• 1 slice bread = 15-20g carbohydrate

Starchy Bread, potatoes, pasta, rice, cereal

SugarySugar, soft drinks, honey, syrups, fruit juices, smoothies, cakes , biscuits, sweets etc

Definition of a low carb diet

Carbohydrate: g/day

Carbohydrate: % energy *

Very low carbohydrate

20-50g 6-10%

Low carbohydrate <130g <26%Moderate carbohydrate

130-225g 26-45%

High carbohydrate

>225g >45%

*based on 2000kcal diet

Benefits of low carb diets

Weight loss Improved glycaemic control

Reduced requirement for diabetes medications

Improved lipid profile

Drawbacks to low carb diets

•Side effects – halitosis, constipation, lethargy

•Low fibre•Can be expensive•Not sustainable for some patients

DUK nutrition guidelines -March 2018• There is no one size fits all prescriptive approach to

making food choices• Food choices should be acceptable and enjoyable

while also helping to achieve treatment goals and improve health and QoL

• An individual approach is needed to promote healthful food choices

BDA position statement on low carb diets - November 2018• Low carbohydrate diets can be effective in

managing weight, improving glycaemic control and cardiovascular risk in people with T2 diabetes in the short term i.e. less than 12 months.

• This is probably due to the accompanying reduction in energy intake and subsequent weight loss.

• Weight loss is still the cornerstone of management of T2 diabetes. There is insufficient evidence to indicate that low carb diets are a superior or better approach than other strategies for weight loss and subsequent weight maintenance in the long term.

BDA position statement continued• The diets of people with T2 diabetes should be

individualised (NICE 2018).• The ideal amounts of carbohydrate for each

individual will be affected by factors such as:• Individual dietary preferences• Current and future diabetes treatment• BMI and the amount of weight that needs to be lost• Individual glucose response• Physical activity levels

Patients with T2 diabetes should be supported to:• Choose a variety of food so that the diet is

nutritionally complete. This includes fruit, veg, dairy foods, seafood, pulses and nuts.

• Moderate their intake of red meat and reduce intake of processed meat, sugar-sweetened foods, particularly sugar sweetened drinks and refined grains such as white bread.

• Ensure fat comes from mainly unsaturated sources, whilst limiting saturated fat intake.

• Include foods high in fibre.

What advice are patients currently

being given in general practice?

What does a low carb diet look like?

• 130g carbs• 86g fat• 1600kcals• 30g fibre• 750mg calcium• 9mg iron

Breakfast Porridge made with 25g oats, 200ml milk, 1 tbsp linseeds

Mid morning

Small banana

Lunch Egg sandwich (2 slices granary bread butter, 1 tsp mayo), green salad with avocado, pear

Mid afternoon

30g almonds

Dinner Salmon, 2 potatoes, carrots, broccoli, yoghurt

Evening 15 grapes

Low carb meal plan app

• 35 g carbs• 57g fat• 1000 kcals• 21 g fibre• 800 mg calcium• 9mg iron

Breakfast Omega boosting Greek yoghurt (raspberries, almond butter, linseeds)

Lunch Tuna and avocado wraps (avocado, yoghurt, tuna, lettuce, cheese, other salad, veg)

Dinner Courgetti spaghetti bolognaise (beef mince, courgettes, cheese, olive oil, onions, tinned tomatoes, peppers, marmite)

Carb content of some foodsCarb content per 80g portion

Bananas 10

Pears 9

Apples 8

15 Grapes 12

Mango 11

Blueberries 7

Honeydew melon 5

Raspberries 4

Turnip/swede/carrots 5

Cabbage 2

So what to advise?

• Dr Unwins low carb program app gives sensible advice:

Low carb program:• Avoid all fizzy pop and sugary drinks• Avoid adding extra sugar to your food or drinks• Cut out the sugary snacks• Go for a 10 min walk after meals 2/week• Allocate ¼ of your plate to starchy carbs, another ¼ to protein and half

to veg• When you eat slow down• Avoid unconscious eating• Eat less processed food and more real food• Eat healthy snacks eg handful of unsalted nuts, single piece of fruit• Have healthy fats eg olive oil• Veg doesn’t need to be boring

Low carb program:• However it also recommends:• Eating plenty of fatty meat and processed meat is

good because it is high in fat so is good at keeping you full

• To avoid wholegrains• Lard and coconut oil

Other guidelines to be mindful of:• Dietary fibre and wholegrains: increased intakes of

total dietary fibre, particularly cereal fibre and wholegrains are associated with lower risk of cardiometabolic disease and colorectal cancer. Aim 30g fibre/day. (SACN Carbohydrates and Health 2015)

• Red meat and processed meat: strong evidence of association between red meat and processed meat and colorectal cancer. Red meat should be limited to 70g/day and very little, if any processed meat should be consumed. (WHO 2015)

Other guidelines to be mindful of:• Fat. Draft report of SACN Saturated Fats and Health

May 2018 continues to advise that saturated fat should be limited to 10% energy and that saturated fat should be replaced with unsaturated fat.

Other useful resources:• Carbs and cals book/app

When NOT to advise a low carb diet

When someone does not need to lose

weight

Anyone at risk of malnutrition

particularly the elderly

Not for pregnant or breastfeeding women Not if kidney disease

Not if eating disorder

Low carb and malnutrition case study• 81 year old gentleman diagnosed with T2 diabetes

HbA1c 48mmol/mol, weight 62 kg, BMI 22 kg/m2. Advised to go on low carb diet by GP.

• He cut out cakes, biscuits, reduced potatoes, bread and weight subsequently reduced to 57 kg, BMI 20 kg/m2.

• Referred to dietitian for nutrition support as mobility had worsened, now walking with a stick, patient concerned about loss of muscle mass.

Physical and psycho-social effects of malnutrition

Adverse effect Consequence

Impaired immune responses Predisposes to infection and impairs recovery when infected.

Impaired wound healing Prolonged recovery of wounds, pressure sores and surgical procedures. Leading to prolonged recovery from illness and increased length of hospital stay.

Reduced muscle strength and fatigue

Inactivity, inability to work effectively and poor self care. Abnormal muscle or neuromuscular function may also predispose to falls or other accidents.

Reduced respiratory muscle strength

Poor cough pressure, predisposing to and delaying recovery from chest infections.

Inactivity, especially in bedbound patients

Predisposes to pressure sores andthromboembolism and muscle wasting.

Impaired thermoregulation Hypothermia and falls, especially in older people

Impaired psycho-social function

apathy, depression, self neglect, hypochondriasis, lack of self esteem, poor body image, loss of interest in food.

Key points

• Individual advice• Low carb diet one of many diets for weight loss.

Good option if got a lot of weight to lose• Discuss which option might be best for the patient• Cutting down not cutting out carbs• Do not advise low carb if patient is already

underweight/at risk of malnutrition• If in doubt – refer to diabetes dietitian

References• Diabetes UK Evidence Based Nutrition Guidelines for the Prevention and

Management of Diabetes. Diabetes UK, Diabet Med. 2018 May;35(5):541-547.• Low Carbohydrate Diets for the Management of Type 2 Diabetes in Adults.

British Dietetic Association 2018 Nov, available from: https://www.bda.uk.com/improvinghealth/healthprofessionals/policy_statements/policy_statement_-_low_carbohydrate_diets_t2_diabetes

• Carbohydrates and Health. Scientific Advisory Committee on Nutrition 2015; TSO• Red and Processed Meat. IARC Monographs on the evaluation of carcinogenic

risks to humans. International Agency for Research on Cancer, World Health Organisation , 2018. Available from: https://monographs.iarc.fr/wp-content/uploads/2018/06/mono114.pdf

• Draft Report Saturated Fats and Health. Scientific Advisory Committee on Nutrition 2018. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/704522/Draft_report_-_SACN_Saturated_Fats_and_Health.pdf

• Carbs and Cals. Chris Cheyette and Yello Baliola 2016, Chello Publishing Limited