Weight Loss: Diets Flashcards
What is the suggestion for nutrition recommendations for adults of all body sizes, according to the CMAJ 2020 Obesity Guidelines?
Nutrition recommendations should be personalized to meet individual values, preferences, and treatment goals, supporting a dietary approach that is safe, effective, nutritionally adequate, culturally acceptable, and affordable for long-term adherence.
What is the role of a registered dietitian in treating obesity?
Adults with obesity should receive individualized medical nutrition therapy from a registered dietitian (when available) to improve weight outcomes (body weight, BMI), waist circumference, glycemic control, and established lipid and blood pressure targets. Registered dietitians may also help adults reduce body weight and waist circumference and improve glycemic control and blood pressure if they have impaired glucose tolerance (prediabetes) or type 2 diabetes
What should adults living with obesity consider when choosing medical nutrition therapies?
They can consider any of multiple medical nutrition therapies to improve health-related outcomes, choosing the dietary patterns and food-based approaches that support their best long-term adherence
What is the recommendation for adults with obesity and impaired glucose tolerance (prediabetes) regarding behavioral interventions?
They should consider intensive behavioral interventions that target a 5%–7% weight loss to improve glycemic control, blood pressure and blood lipid targets and reduce the incidence of type 2 diabetes, microvascular complications, and cardiovascular and all-cause mortality
What is the recommendation for adults with obesity and type 2 diabetes regarding lifestyle interventions?
They should consider intensive lifestyle interventions that target a 7%–15% weight loss, to increase the remission of type 2 diabetes and reduce the incidence of nephropathy, obstructive sleep apnea, and depression
What is the recommended approach to improve quality of life and psychological outcomes?
A nondieting approach is recommended to improve quality of life, psychological outcomes (general well-being, body image perceptions), cardiovascular outcomes, body weight, physical activity, cognitive restraint, and eating behaviors.
Define “diet”
The sum of food and drink they habitually consume. Dieting is the practice of attempting to achieve or maintain a certain weight through nutritional intake. People’s dietary choices are often affected by a variety of factors, including ethical and religious beliefs, clinical need, etc
List the types of diets that will be discussed
Vegetarian diets, low fat diets, low carbohydrate diets, high protein diets, very low calorie diets, and crash diets
What is a vegetarian diet?
A vegetarian diet is one which excludes meat and animal by-products (e.g., gelatin and rennet)
Name four variations of vegetarian diets
Fruitarian diet, Lactovegetarian, Lacto-ovo vegetarian, Vegan diet
What does a vegan diet consist of?
Contains only plants and foods made from plants, excluding any food derived from animals (e.g., eggs). Vegans need to ensure they get sufficient iron and other vitamins
What is a semi-vegetarian diet?
Predominantly vegetarian diet but meat is occasionally consumed
What is a pescetarian diet?
A diet which includes fish but not meat
What are the potential advantages of vegetarian diets?
Lower level of saturated fats, lower consumption of added sugar, low or no consumption of cholesterol, high intake of fibre, magnesium, potassium, folate, antioxidants, and phytochemicals. On average, vegetarians have lower reported BMI and have a lower odds of mortality from heart disease and lower rates of hypertension, T2D, and certain cancers
What are the potential disadvantages of vegetarian diets?
Limiting foods makes adequate consumption of nutrients more difficult. There’s a risk of vitamin B12 deficiency and inadequate vitamin D consumption if no dairy is consumed (especially problematic for kids). It can be hard to consume an adequate amount of calories, and there is a high risk of iron deficiency anemia and risk of protein deficiencies
What should be considered in regards to appetite and plant-based diets?
Plant-based diets can have similar feelings of hunger, satisfaction, and weight loss to other diets
What should be considered in regards to weight loss and plant-based diets?
Vegan groups have shown to have a greater reduction in weight, fat mass, VAT and HOMA compared to control groups. The impact of carbohydrate is related to the amount of dietary fibre. Plant-based diets can be associated with weight loss because they are typically less dense calorically than other foods (feel fuller sooner due to volume)
What considerations need to be made regarding vegetarian diets and food choices?
Foods like candy, cupcakes, cookies and other processed foods are technically vegetarian, so it often comes down to food choices
What is a low-fat diet?
Normally, less than 30% of energy intake (EI) from fat (some say 10-15%). May also include less than 10% EI from saturated fat, no trans fats, and controlled cholesterol intake
Why might a low-fat diet work?
Energy density (cheese vs. vegetables), efficiency of storing fat as fat, low thermic effect of feeding of fat, taste/texture, and potentially low satiety
Why might a low-fat diet not work?
Palatability, high carbohydrate/sugar content, and the fact that fat intake has decreased while obesity rates have increased. Fat can have high satiety depending on amount of fat, fatty acid chain length, degree of saturation and what it is eaten with (fiber, CHO, sugar)
What evidence supports the effectiveness of low-fat diets?
Randomized, controlled trials (RCTs) and meta-analyses. For each 1% reduction in %fat intake there is approximately 1.6g/day of weight loss. Low fat diet combined with energy restriction can lead to more weight loss than Low fat diet alone
What are the metabolic reasons that low-fat diets are preferred for?
Low-fat diets are preferred for metabolic reasons because they uncouple fat intake and oxidation (dietary fat intake above energy requirements is stored in adipose tissue). Also, high fat foods or energy dense foods have weak satiety effects and promote overconsumption
What are the benefits of low-fat diets?
Low fat diets are helpful for weight loss and may help with maintained weight loss (low fat + low energy diets are even better) and may be associated with type of fat (unsaturated vs. saturated). Low fat diets are good for heart health and certain cancers
What are the potential negative side effects of low-fat diets?
It’s difficult to say to what extent benefits and negative side effects are due to weight loss or low fat intake. Also, low palatability, and potential issues with essential fatty acids, liposoluble vitamins, and HDL. Few studies have shown large long-term effects on weight loss, so it may be better for prevention of weight gain than loss
What is a low-carbohydrate diet?
Some consider it to be less than 20 g CHO/day for 2 weeks then <50g/day (Atkins) with ad libidum intake of fat and animal protein. There is no universal definition
What are the other definitions of low-carbohydrate diets?
Reduced carbohydrate diet: >130 g of carbohydrate per day, up to 45% of total calories. Low carbohydrate diet: 30-130 g of carbohydrate per day. Very low-carbohydrate ketogenic(VLCK) diet: <30g of carbs/day; will usually permit ketosis to occur
Why might a low-carbohydrate diet work?
Promotes adipose tissue metabolism when CHO is absent. Ketones are produced when burning fat (ie. Not enough CHO); interacts with incretine hormones (CCK/ghrelin) to suppress appetite. Also may result in rapid weight loss due to appetite suppression and water loss (1-2kg in 7-14 days)
What does the NEJM study suggest about ketones?
Ketones were not related to weight loss and low CHO (conventional) diet has lower calories
What has been observed regarding hunger after 1 month on a low-carbohydrate diet?
Lower rates of hunger
Why might a low-carbohydrate diet not work?
Too restrictive, unlikely to be adhered to long-term, concerns with high meat consumption, discouraging after initial success slows down, potential for nutritional inadequacies, and potential interference with higher amounts of training
What did the Nordmann (2006) meta-analysis of RCTs reveal about low-fat vs low-carbohydrate diets?
At 6 months low fat diets = -3.3kg (vs. low CHO). At 12 months no significant difference between groups. Low CHO diets better for HDL and TG, while low fat diets are better for LDL and total cholesterol
What are the negative side effects of low-carbohydrate diets?
Less improvement in LDL-Chol (vs. low fat), increased calcium excretion and homocysteine, low energy, bad breath, and cancer risks.
What do more recent long term adherence studies suggest about low-carbohydrate diets?
Similar body weight and body composition, but a greater improvement in HDL at 2 years
What is an interesting avenue for future research regarding low-carbohydrate diets?
People with high insulin response to 75g OGTT lost more weight on low CHO diet
How are high-protein diets defined?
They are not as consistently defined in the literature and are often hard to distinguish from low carb diets. Could be defined as >25% of kcal from protein or >1.2 g protein per kg of body weight
Why might high-protein diets work?
High satiety, energy demanding to store excess protein, can taste good, and preserve fat free mass
Why might high-protein diets not work?
Concerns with high meat consumption and potentially costly.
What is the evidence regarding the effectiveness of high-protein diets?
Recent studies suggests high protein may be particularly helpful for prevention of weight regain
What are the risks associated with high-protein diets?
Often similar to low carbohydrates and safety issues with some protein supplements. Excess protein is hard on the kidneys and can contribute to dehydration
What are the health issues associated with high meat consumption?
High temperature cooking produces carcinogens. Haem Iron (found in red meat and is easy to absorb; non-haem is vegetable based proteins).
What are the risks related to consumption of red and processed meats?
“17% increased risk per 100 g per day of red meat” and “18% increase per 50 g per day of processed meat”
What is a Very Low Calorie Diet (VLCD)?
More recently defined as < 800 kcal… or <50% of RMR
Who are VLCDs for?
BMI > 30 kg/m2 at risk of diabetes/CVD, no medical and behavioral contraindications, non-pregnant, people who have money (expensive), and those who can adhere
Why might VLCDs work?
“Simple” to follow, no food preparation, no calorie counting, large energy deficit, rapid weight loss can be motivating, could be a starting point to other changes (e.g., exercise), and help break eating habits or “addictions”
Why might VLCDs not work?
Not a long-term solution, no changes in behaviors, very costly, must be medically supervised, and safety concerns
What is the evidence regarding the effectiveness of VLCDs?
Rapid weight loss, but long term weight loss <,=, or > LCD. Patients generally regained 40% to 50% of lost weight 1 to 2 years after treatment, in the absence of follow-up care
What are the negative side effects of VLCDs?
Gallstones, cold intolerance, hair loss, headache, fatigue, dizziness, volume depletion (with electrolyte abnormalities), muscle cramps, and constipation
What are some examples of crash or fad diets?
Cabbage soup diet, grapefruit Diet, master Cleanse Diet, fat flush diet
What are the characteristics of crash diets?
Often very low in calories, deficient in nutrients, and not sustainable
What was assessed in the comparison of common diets (Atkins, Zone, Weight Watchers, Ornish)?
Adherence rates and the effectiveness for weight loss and cardiac risk
What were the findings of the comparison of common diets?
Adherence and weight loss were similar between all diets, and adherence was key
What is the key to weight/fat loss?
All diets that cause weight/fat loss reduce energy intake (EI). Typically, the more foods are restricted the more EI decreases
What factors should be considered when choosing a diet?
Some people may respond more favorably to some diets than others (palatability, hunger, physiology, behavioral/socio/cultural issues, genetics). Also consider the risk benefit ratio and long term sustainability.
Can different approaches be used for different phases of weight management?
Can use different approaches for initial weight loss vs. long term sustainability
