Body fat (BF) and muscle mass showed opposing association with mortality. Whole-food, plant-based (WFPB) lifestyle programs has been on the rise lately especially due to impressive health benefits.

The results of research on the effectiveness of popular weight loss diets in obese subjects showed 20 to 30% loss of lean muscle mass within to the total body weight loss, whereas in the whole-food, plant-based (vegan) diet the loss was up to 42%.

Therefore, an open research problem is to find a way how to improve body composition in an effective and healthy way (i.e., losing of excess BF while maintaining muscle mass as much as possible) but still using stric plant-based (vegan) diet.

Investigators will perform retrospective analysis of measurements of body composition and phase angle values of aprox. 200 participants who were on a WFPB lifestyle program from 2016 to 2021 and performed two successive measurements (initial and follow up (FU)), without body mass index (BMI) limitation on same medically approved and calibrated bioelectrical impedance (Tanita 780 S MA, Tokyo, Japan) and were not yet included in our previous studies. A WFPB lifestyle program were consisted of nutrition (i), (ii) physical activity and (iii) support system.

Primary outcome include the following measures: BF % and FFM and to examine the change from initial values to FU values (by gender), according BMI classification (e.g,, normal, pre-obese and obese) with subanalysis for those participants who lost up to 5 kg/more and those who lost 5 kg or more of body weight.

Many people are increasingly using a variety of dietary practices to manage overweight and obesity. Many people are increasingly using a variety of dietary practices to manage overweight and obesity.

Investigators will investigate the muscle mass preservation of participants on our 12-year lasting ongoing, community-based (free-living), WFPB lifestyle program during the weight/fat loss of participants.

The primary outcome is the BF %, and FFM change from initial values to FU values (for whole sample and by gender).

Secondary outcome include correlation between BMI, BF % and FFM, and PhA. Based on our experiences we believe that some participants that follow our WFPB lifestyle program may initially "afraid" to eat, according to the instructions, each meal to satiety (ad libitum). The reason lies in the typical weight loss recommendation in Western-type lifestyle that advise "eating less".

The body composition measures will include body height (BH; measured via standardized medical approved professional personal floor scale with stand (Kern, MPE 250K100HM, Kern & Sohn, Balingen, Germany), body mass (BM), BF mass and BF %, FFM, bone mineral mass (BMM), visceral fat (VF), total body water (TBW), extracellular water (ECW), intracellular water (ICW), the ratio, whole body phase angle (PhA), all via medically approved and calibrated bioelectrical impedance Tanita 780 S MA (Tanita Corporation, Tokyo, Japan) and the use of corresponding protocols (e.g., for BMI).

Inclusion Criteria:

• Using WFPB lifestyle program.
• Were measured on a body composition analyzer at least two successive times on the same body composition montor Tanita 780 S MA, Tokyo, Japan (at baseline, follow up) in a row at different intervals (i.e., before the start of the program and as part of follow up).
• Follow up up to 6 months
• Baseline BMI status was not an exclusion criteria.
• Data of participants that did not participate yet in our previous research.
• No medication use

If the individual performed more than two consecutive measurements, only the first two were included in the analysis.

Exclusion Criteria:

• Being on vegan diet before joined in our program.
• Being adult (e.g., older than 18-years) before the start of the program.
• Participating in our preivous research using WFPB lifestyle program.
• Without severe chronic diseases or physical limitations (described bellow).

We will examine the body composition data of healthy adults from Slovenia (European Union) that were without preference toward plant-based diet before entering to the program. As healthy adults we mean that used data were from participants without serious comorbidities (i.e., having autoimmune or neurodegenerative disorders), physical limitations or taking medicine (for blood pressure, blood sugar or cholesterol).