Early-day Protein Intake Influences the Transition of Metabolic Health Phenotypes Among Adults with Obesity

Metabolically healthy obesity (MHO) represents a subset of obesity characterized by a lower risk of cardiometabolic syndrome than individuals with metabolically unhealthy obesity (MUO). This study aimed to (1) describe the transition of metabolic health phenotypes in adults with obesity and (2) identify the differentiating factors associated with this transition following the 12-week weight reduction program. This study recruited 91 adults with obesity (Age: 39.6±6.3 years; 74.7% women; body mass index (BMI): 31.2±4.5 kg/m2). The weight reduction intervention incorporates multiple lifestyle domains, including dietary modifications, physical activity, behavioural strategies, and chrono-nutrition, which encompasses temporal eating patterns, meal timing and sleep. At pre-intervention, 55% of participants (n=50) were classified as MHO: BMI≥25kg/m2 with fewer than three metabolic abnormalities, while 45% (n=41) were classified as MUO: BMI≥25kg/m2 with three or more metabolic abnormalities. Post-intervention, about 24% of the participants (n=22) exhibited positive changes, transitioning from MUO to MHO or from MUO/MHO to metabolically healthy normal weight (MHN). The MUO proportion decreased to 31% (n=28), and 45% (n=41) remained as MHO. Participants who demonstrated positive changes were characterized with highest increase in energy intake from protein sources (+5.2% vs +1.1%, p=0.004), particularly during the earlier part of the day (+4.3% vs +1.1%, p=0.029), greater body weight loss (-7.0% vs -3.2%, p=0.022), body fat loss (-3.4% vs -1.3%, p=0.013) and visceral fat loss (-1.3 vs -0.5, p=0.013) as well as a higher proportion of morning chronotype (72.7% vs 35.7%, p=0.033), than the participants who showed negative changes. These results imply that, the timing of protein intake and chronotype may play significant roles in mitigating the risk of cardiometabolic syndrome among adults with obesity, in addition to weight reduction.