Comparing a Low-GI Nutrigenetic and Ketogenic Diet for Weight Loss With 18 Month Follow-up
Condition: Weight Loss; Glucose, High Blood; LDL Hyperlipoproteinemia; HDL; Triglycerides High
MeSH terms: Hyperlipoproteinemias; Hyperlipidemias; Body Weight; Weight Loss
Study type: Observational

Summary: 
      The investigators followed a convenience sample of 114 overweight and obese subjects from a
      weight loss clinic who followed a 24-week dietary intervention. The subjects self-selected
      whether to follow a standardized ketogenic diet (n=53), or a personalised low-glycemic index
      (GI) diet utilising information from 28 single nucleotide polymorphisms (n=61). After the
      24-week study period, the subjects were monitored for an additional 18 months.
    

Detailed description: 
      In the present study, the investigators followed patients in a clinic who self-selected
      either a ketogenic diet with no nutrigenetic modification, or a low glycemic index (GI) based
      diet with nutrigenetic modifications. The addition of nutrigenetic advice was not designed
      nor proposed to patients as a weight loss diet, nor to predict either disease risk or obesity
      risk; the aim was simply to optimize the nutrient content of an individual's daily food
      intake, based on current understanding of an individual's genetic profile. The aim of this
      study, therefore, was to compare the performance of the well-known, and generally the most
      effective in the short-term [25], ketogenic diet to a low-GI nutrigenetic diet. A ketogenic
      diet has also shown to have long-term (12 months) effectiveness for weight loss [26],
      although the effects of the diet over a longer time period than this are currently unclear.

      114 overweight (n=1) and obese (n=113) subjects (M = 55, F = 59, age 24-56y, all of Romanian
      heritage and similar socio-economic status), who were patients at a weight management clinic
      (Bucharest, Romania), gave written informed consent for their weight loss data to be
      prospectively analysed for this study. All patient data were handled according to the
      Romanian Code of Medical Deontology and in accordance with the Helsinki Agreement. Approval
      was given by the Ethics Committee of the University and Pharmacy, Cluj Napoca, Romania
      (registration number 444). Upon enrolment at the weight management clinic, the subjects
      self-selected either a ketogenic diet or a low-GI nutrigenetic diet. A ketogenic diet was
      utilised as the comparison diet due to its reported efficacy in the treatment of obesity
      [26]. Fifty-three subjects (25 female; age 43.0 ± 7.2y) selected the ketogenic diet plan, and
      61 subjects (34 female; age 42.0 ± 6.7y) selected the low-GI nutrigenetic diet plan. Subjects
      in the low-GI nutrigenetic diet group underwent DNA testing (NutriGENE by Eurogenetica
      Ltd/DNAfit, UK) for 28 Single Nucleotide Polymorphisms (SNPs) in 22 genes with good evidence
      of gene-diet/lifestyle interactions [table 1]. Overall participation in both diet groups cost
      a similar amount, comprised of approximately €300 for the genetic test along with 1-month
      diet plan, initial evaluation, body composition, and medical history for the nutrigenetic
      group, and €280 for the ketogenic group, providing Ketostix and the same evaluations. Further
      visits through the 24-week program the overall cost per patient was approximately €800. After
      24 weeks diet follow up visits had no further cost.

      After the 24-week study period, the subjects were monitored for an additional 18 months.

      At the study onset, patients were not type 1 or type 2 diabetics, although many were
      hyperglycemic, which is a common issue in obese subjects. Any patients with records of any
      other disease were excluded prior to commencing the dietary intervention. The patients, apart
      from obesity, were otherwise "healthy".
    

Intervention name(s): weight loss diets
Intervention type(s): Other
Intervention description(s): The ketogenic diet group were instructed to consume <35g of carbohydrates per day, and <10% of total calories were from saturated fats. Daily protein intake was set at 1.2g/kg bodyweight for females, and 1.5g/kg bodyweight for males. The low-GI nutrigenetic diet group had individualised dietary instructions based on their genetic results
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Probability Sample
Study population: 
        114 overweight (n=1) and obese (n=113) subjects (M = 55, F = 59, age 24-56y, all of
        Romanian heritage and similar socio-economic status
      
Biospecimen description: 
      buccal swab for DNA, venous blood for cholesterol & glucose
    
Keywords: Glycaemic index; nutrigenetics; weight loss; ketogenic; nutrigenomics