Gene-Environment Interaction and Precision Nutrition on Adiposity, Glycemic, Lipids Changes, and Bone Health

The purpose of this study is to test the interactions between the genes and diet interventions varying in macronutrient intake on glycemic, waist circumference, body weight, visceral fat and lipids changes. In the POUNDS LOST, all of the 811 participants DNA was extracted from the buffy coat fraction of centrifuged blood using the QIAmp blood kit (Qiagen, Chatsworth, CA). Single nucleotide polymorphisms were genotyped using the OpenArray™ SNP genotyping system (BioTrove, Woburn, MA). The study is only accepting participants in the Boston, Massachusetts or Baton Rouge, Louisiana area. For further enrollment information in Boston or Baton Rouge, see Eligibility Criteria or Design Narrative.

Besides, the investigators integrated novel pathway analyses in large cohorts and comprehensive genetic analyses on long-term weight loss and mechanisms in randomized diet intervention trials would provide very important evidence to unravel the etiology of obesity, and have significant public health and clinical implications. Establishing relationship between genetic variants and diets in determining weight change will help identify individuals at high risk for obesity especially when adherent to specific diet.

The epidemic of obesity has become a major public health problem. Obesity is a multifactorial abnormality that has a genetic basis but requires environmental influences to manifest. Common-form obesity is underpinned by both environmental and genetic factors. Recent genome-wide association studies have identified several genes convincingly related to obesity risk. Testing gene-environment interaction is a relatively new field. Evidence from association studies and intervention trials continues to mount, indicating that genetic components may modify lifestyle effects on the development of obesity. However, these findings are at most preliminary. The interplay between genetic and environmental components may facilitate the choice of more effective and specific measures for obesity prevention based on personalized genetic make-up.

The investigators aimed to examine whether the genetic variation affected glycemic, waist circumference, body weight, visceral fat and lipids changes in response to weight-loss dietary intervention varying in macronutrient intake (target percentages of energy derived from fat, protein, and carbohydrate in the 4 diets were as follows 20%, 15% and 65%; 20%, 25%, and 55%; 40%, 15%, and 45%; and 40%, 25%, and 35%).

The primary outcome is to test the interactions between the genes and diet interventions varying in macronutrient intake on body weight changes. The secondary outcome is to test the interactions between the genes and diet interventions varying in macronutrient intake on glycemic, waist circumference, visceral fat, and lipids changes. Understanding gene-diet interactions in relation to weight loss hold great promise for delivering more efficient prevention and treatment on obesity and related metabolic disorders.

In addition, besides gene-diet interactions, the investigators will also conduct other precision nutrition analysis. These analyses include interactions between pretreatment factors with diet intervention adiposity traits, initial changes induced by diet intervention with various outcomes measured in POUNDS Lost, including body weight, waist circumference, body composition, ectopic fat, and bone health.

Eligibility Criteria:
Inclusion Criteria:

* Only accepting participants in the Boston, Massachusetts or Baton Rouge, Louisiana area
* Between the ages of 30 - 70
* Willing to modify eating pattern according to instructions
* Overweight or obese and in good health with a BMI of 25-40
* Committed to a long-term weight loss and maintenance program
* Willing to attend multiple weight loss group sessions
* Willing to increase activity level

Exclusion Criteria:

* Pregnant, planning to become pregnant, or are breastfeeding
* Unwilling to participate in the schedule of group sessions and individual visits
* Unstable or recent onset of heart disease or any other serious illness
* Cannot change diet due to medical or other reasons
* Planning to leave the area prior to the anticipated end of participation
* Current participation in another clinical trial with an intervention that affects weight change
* Have diabetes that is treated with insulin or hypoglycemic oral medicines
* Diagnosis of psychiatric or emotional problems within 6 months of study
* Currently have an eating disorder
* Have hypothyroidism
* Have an unstable weight