Ketogenic/Low Carbohydrate diets for weight loss- What s the big deal? Presented by Claudia Harper APD Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders The University of Sydney Page 1
Another strategy or another fad? Over the preceding years there have been many strategies and interventions proposed and tried with an aim to reduce energy intake and for increasing energy output. Many dietary interventions much confusion and controversy in the population Is a ketogenic diet the answer for obesity? The University of Sydney Page 2
What is a ketogenic diet? A diet that induces a metabolic state known as ketosis Used in epilepsy Atkins LowCarb/HighFat Ketosis = higher than normal circulating ketones in blood (ketone bodies) ~0.3mmol/L beta-hydroxybutyrate in blood Ketosis can occur in hyper, hypo or eucaloric diets Needs low carb or very low energy (or both) to induce ketosis The University of Sydney Page 3
Ketosis Glucose is usual source of energy Once glucose sources (exogenous and endogenous) are depleted the liver produces ketone bodies as a fuel source The University of Sydney Page 4 http://richmansgym.com/2016/03/happens-body-ketosis/
Traditional ketogenic diet ~80-90% of total kjs from fat, moderate protein and 20-50gms CHO/day or 2-10% of total kjs 1 8400kJ diet (3:1)= ~190gm fat, ~25gm CHO, ~50gm protein Various versions have become a popular weight loss method in the lay population and are usually <50gms CHO Very low energy diet <3350kJ (800kcal) / day total meal replacement ~60-80gm CHO per day/moderate protein/low fat The University of Sydney Page 5 1. Roehl K, Sewak SL. Practice Paper of the Academy of Nutrition and Dietetics: Classic and Modified Ketogenic Diets for Treatment of Epilepsy. J Acad Nutr Diet. 2017 Aug;117(8):1279-1292.
Very low carbohydrate ketogenic diet v low fat diet for long term weight loss: a meta analysis of randomised controlled trials 2 13 RCTs, 1,569 participants, minimum follow up of 12 months A very low carbohydrate ketogenic diet was defined as a diet with no more than 50g of carbohydrates per day or 10% of daily energy from carbohydrates, ad libitum fat/protein A low fat diet was defined as a restricted energy diet with less than 30% of energy from fat 2. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very low carbohydrate ketogenic diet v low fat diet for long term weight loss: a meta analysis of randomised controlled trials. British Journal of Nutrition.2013;110(7):1178 1187. The University of Sydney Page 6
Meta-analysis Results 2 Patients assigned to a very low carbohydrate ketogenic diet had statistically significant greater weight loss than those assigned to a low fat diet (WMD 0.91kg, 95% CI 1.65 to 0.17) at 1 year 2. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very low carbohydrate ketogenic diet v low fat diet for long term weight loss: a meta analysis of randomised controlled trials. British Journal of The University of Sydney Page 7 Nutrition.2013;110(7):1178 1187.
Meta-analysis- results Also low carb had TGLs, diastolic BP and LDL, HDL No significant difference between low carb vs low fat : Systolic BP, Fasting BGL, insulin, HbA1c, C-RP No statistical significance at 24 months (4 trials) The University of Sydney Page 8
Meta analysis Conclusion 2 The authors acknowledged that in the long term and when compared with conventional therapy, the results appeared to be of little clinical significance despite their statistical significance (such as weight loss of 0.91kg) One limitation: Adherence to very low carb keto diet in the included studies was low. At the end of the follow-up period in most studies, carbohydrate intake was higher than the protocol allowed reported between 9-47% of energy. 2. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very low carbohydrate ketogenic diet v low fat diet for long term weight loss: a meta analysis of randomised controlled trials. British Journal of Nutrition.2013;110(7):1178 1187. The University of Sydney Page 9
Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a metaanalysis of randomised controlled trials 3 11 RCTs, 1369 subjects, minimum follow up 6 months LC: Atkins 20-40g/d of CHO in first phase or CHO < 20% of total energy intake; ad libitum fat/protein LF: variations of a conventional LF diet Interventions 20 subjects/group; healthy The meta-analysis has 7 studies in common with Bueno et al. meta analysis (2013) 3.Mansoor The University N,Winknew of Sydney KJ, Veierod MB, Retterstol K. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. Page British 10Journal of Nutrition. 2016, 115, 466-479.
Meta-analysis Results 3 Significant greater weight loss in LC vs LF (WMD:-2.17kg; 95%, CI -3.36,-0.99) The University of Sydney Page 11
Meta-analysis Results + Conclusions Also LC vs LF : Significantly TAG; LDL; HDL No significant difference : Total Cholesterol, SBP, DBP, glucose and insulin In Summary Low carbohydrate diets offer significant weight loss advantage (2.17kg) however this must be weighed against increase in LDL which is atherogenic. Limitations: As with previous meta-analysis adherence was low by the end of the trials reported CHO 9-40% The University of Sydney Page 12
Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial 4 12 week diet intervention, follow up to 52 weeks Both diets individualized with 30% restriction LC : n=58 HC: n=57 LC diet: 14% of total energy CHO (<50g/d), 28% protein, 58% fat (mono & poly) HC diet: 53% of total energy CHO ( low GI), 17% protein, <30% fat (mono & poly) Both diets limited sat fat <10% of energy The University of Sydney Page 13 4. Tay J, Luscombe-Marsh ND, Thompson CH, Noakes M,Buckley JD, Wittert GA, Yancy WS, Brinkworth GD. Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trialam J Clin Nutr 2015;102:780 90
Cont. Both groups had same amount of dietetic support (a lot) Food records were completed daily Key foods or $50 vouchers provided on alternate months Supervised exercise classes 3 x weekly Reported dietary intake were consistent with planned diets; energy intakes did not differ between groups. The University of Sydney Page 14
Estimated mean (95% CI) marginal changes in body weight after 52 wk of consumption of an LC or HC diet on the basis of a linear mixed-effects model (n = 115). Jeannie Tay et al. Am J Clin Nutr 2015;102:780-790 2015 by American Society for Nutrition
Results cont. HbA1c and fasting BGL similarly reduced (HC/LC) LC achieved greater reduction in antiglycemic medication effect score (P=0.02) LC vs HC - TGL, HDL Similar reductions in TC, LDL, BP Conclusion: with careful planning and support a low carb diet can be effective at weight loss without increasing CVD risk. The University of Sydney Page 16
Appetite control of ad libitum ketogenic diets There is a lot of anecdotal evidence online that the magic of low carb ketogenic diets allows you to eat ad libitum and you will lose weight because your appetite is controlled by ketosis. While ketogenic VLEDs have shown to significantly reduce appetite and hunger during weight loss the level of evidence for ad libitum low carbohydrate ketogenic diets is limited 3 LC diets that assessed subjective hunger using visual analogue scale (VAS) The University of Sydney Page 17
Effects of a high-protein ketogenic diet on intake and weight loss in obese men feeding ad libitum 5 High-protein, low-carbohydrate ketogenic VS high-protein, medium-carbohydrate nonketogenic 17 obese men feeding ad libitum, inpatient residence, randomised crossover design 30 days, 3 days rest, then crossover 30 days. All food was supplied men could eat however much they liked The 5. Johnstone University AM, of Horgan SydneyGW, Murison SD, Bremner DM, Lobley GE; Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Page 18 Am J Clin Nutr 2008;87:44 55
Results Subjects felt significantly (P = 0.014) less hungry ( 4.6 on the VAS) on LC ketogenic diet, although there was a high rate of noncompliance (47%) in filling out the questionnaires Ad libitum energy intakes were lower on LC diet = 694kJ/166kcal/day LC vs MC weight loss- 6.34 kg vs 4.35 kg = 2kg significant difference (35% of difference in water, rest fat loss and some lean mass) The University of Sydney Page 19
Change in Food Cravings, Food Preferences, and Appetite During a Low-Carbohydrate and Low-Fat Diet 6 LC Diet Start at <20g CHO/day, unlimited fat and protein - increasing CHO over time Atkins new revolution protocol LF Diet- kj intake and fat intake. Women prescribed 1,200 1,500 and men 1,500 1,800kcal/day diets. Participants were encouraged to consume ~30% kcal from fat, 15% from protein, and 55% from carbohydrate. 2 year study - Weekly group sessions during weeks 1 20, biweekly sessions during weeks 22 40, and bimonthly sessions during weeks 48 104 Assessed cravings, preferences and appetite The University of Sydney Page 20 6. Martin CK, Rosenbaum D, Han H et al. Change in food cravings, food preferences and appetite during a low carbohydrate and low-fat diet. Obesity 2011; 19;1963-70.
Results a. LC had significantly reduced cravings for carbohydrates d. LF had significantly reduced cravings for high fat food The food that was restricted was the food that cravings were reduced for The University of Sydney Page 21
Results 6 LC had lower preference for carbohydrate LF had lower preference for high protein foods LC bothered less by hunger except at one time point The University of Sydney Page 22 6. Martin CK, Rosenbaum D, Han H et al. Change in food cravings, food preferences and appetite during a low carbohydrate and low-fat diet. Obesity 2011; 19;1963-70.
Cont. No difference in other appetite scales between groups No difference in weight loss between LC and LF at any time point In summary, calorie restriction or food restriction can help with cravings for the food that is restricted - Suggests conditioning and extinguishing of food preferences 1 other LC study found using VAS hunger scale had significant decrease in hunger but no comparison group 7 7. The Ratliff University J, Mutungi of G, Sydney Puglisi MJ, Volek JS, Fernandez ML. Carbohydrate restriction (with or without additional dietary cholesterol provided by eggs) reduces insulin resistance and plasma leptin without Page 23 modifying appetite hormones. Nutr Res 2009; 29: 262-268.
Conclusions Low carbohydrate diets are as effective for weight loss as low fat diets High LDL cholesterol seen with usual LCHF diets may be ameliorated by ensuring saturated fat is <10% of total energy as per guidelines May help reduce medication in people with diabetes May be useful in decreasing subjective hunger Could be used as a stepping stone to a more sustainable lifestyle change The University of Sydney Page 24
THE END The University of Sydney Page 25