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Got 10 mins? Interested in nutrition, T2DM, weight loss and cardiovascular health? What do you advise your patients? Plant based? Low carb? Keto? Confused? Join me for a Twitter journal club discussion! @ProfDFrancis @vass_vassiliou @parthaskar @KevinH_PhD @lowcarbGP @DoctorTro
Background - diet inevitably places a critical role in the development of T2DM and CV disease. Rates of obesity are soaring, which is a strong contributor to both diseases. We should be strong advocates for people eating the right stuff, preventing the disease in the first place!
But what is the right stuff? The area of nutritional ‘expertise’ is full of pseudoscience and fad diets. The DoughnutDoctor is case in point. Surely a good RCT is needed! @KevinH_PhD to the rescue!
Paper: A plant-based, low-fat diet decreases ad libitum energy intake compared to an animal-based, ketogenic diet: An inpatient randomized controlled trial. https://osf.io/preprints/nutrixiv/rdjfb/
Caveat - paper is currently pre-print but comes from the NIH (an institution we can trust).
Caveat - paper is currently pre-print but comes from the NIH (an institution we can trust).
Aim: Investigate impact of two diet protocols (vegan, mainly carb based vs keto, mainly animal based). Primary end point - mean energy intake. Secondary endpoints - weight, fat-free mass, energy expenditure, lipids, triglycerides, blood pressure and glucose tolerance testing.
Methods: RCT, crossover. 20 overweight people, without diabetes, admitted as inpatients. Importantly subjects were not informed of the purpose of the study, to avoid deliberate behavioural effects.
For 2 weeks, half ate vegan (10% fat, 75% carb, 15% protein) whilst the other half ate keto (76% F, 10% C, 14% P). Food/snacks were provided in portions of caloric excess - participants could eat as much or as little as they desired. The groups switched after 2 weeks.
Results:
Primary endpoint: energy intake lower in vegan group by 689 kcal/d.
Primary endpoint: energy intake lower in vegan group by 689 kcal/d.
Some secondary endpoints:
Favouring vegan:
Weight loss (1.09kg/2 weeks) with preservation of fat-free mass
Lower caloric intake whilst satisfaction and fullness maintained
Lower LDL-C (small effect of 0.7 mmol/l)
Better glucose tolerance test
Lower BP (3mmHg SBP)
Favouring vegan:
Weight loss (1.09kg/2 weeks) with preservation of fat-free mass Lower caloric intake whilst satisfaction and fullness maintained Lower LDL-C (small effect of 0.7 mmol/l) Better glucose tolerance test Lower BP (3mmHg SBP)
Favouring keto (mainly animal based):
More steady glucose profile (no peaks/troughs)
Higher basal metabolic rate (166 kcal/d higher)
Lower triglycerides (small effect of 0.3 mmol/l)
More steady glucose profile (no peaks/troughs) Higher basal metabolic rate (166 kcal/d higher) Lower triglycerides (small effect of 0.3 mmol/l)
Strengths:
Rigorous RCT design with lab controlled conditions
Meticulous measurements of calorie intake and expenditure
Vast array of secondary endpoints
Rigorous RCT design with lab controlled conditions Meticulous measurements of calorie intake and expenditure Vast array of secondary endpoints
Weaknesses:
No wash-out period between diets
Longer term implications not known
Lab conditions don’t replicate everyday eating triggers e.g. seeing doughnuts at work.
No wash-out period between dietsLonger term implications not knownLab conditions don’t replicate everyday eating triggers e.g. seeing doughnuts at work.
Conclusions:
Bottom line on diet - we still don’t know. This paper supports the higher carb/lower fat vegan approach but the peaks/troughs in glucose profiles with higher continuous glucose monitoring readings were concerning.
Bottom line on diet - we still don’t know. This paper supports the higher carb/lower fat vegan approach but the peaks/troughs in glucose profiles with higher continuous glucose monitoring readings were concerning.
Intuitively, if one has a disorder of carb metabolism (i.e. T2DM) it would make sense to reduce carbohydrates. The keto group fared worse on the GTT but had a more stable 24-hr blood glucose profile.
Whatever diet approach you take, I think it makes sense to cut refined sugar and cut processed foods. Couple this with the laws of thermodynamics (calories in < calories out) and you will lose weight!
