Researchers from the US, South Africa and Denmark looked at the effect a combined protein-pacing and calorie-restriction (P-CR) programme had on 43 healthy but obese American men and women over a 12-week period.
With a smaller subset of participants over a 52-week period they compared this to a 'heart-healthy' (HH) diet in line with the Therapeutic Lifestyle Changes (TLC) diet backed by the US National Cholesterol Education Programme.
Visceral fat down a third
During the 12-week weight-loss phase, they found participants on average lost 10% of their mass in weight and 33% of their visceral fat, while increasing their lean mass by 9%. Participants’ glucose levels fell 7-12%, insulin by 42% and leptin by more than 50%, while their resting metabolic rate rose 5%.
After the one-year weight maintenance phase, a modified protein-pacing and calorie restriction (mP-CR) regime resulted in 6% lower body weight, 10% total body fat and 17% lower abdominal fat, as well as 5% greater lean mass, compared to participants on a heart-healthy regime.
There were no significant differences in results between men and women during either phase.
“Thus [protein pacing and calorie restriction] should be considered as a viable public health recommendation to facilitate weight loss and prevent weight recidivism in obese men and women,” the researchers wrote in their conclusion.
The team had originally set out to investigate sex-specific differences in response to the P-CR regime, in response to the tendency of P-CR research to focus on women.
During the initial phase of the research, and with approval from participants and academic authorities, the team proposed extending the research to include the longer-term weight management (WM) phase.
Heart-healthy diet saw higher weight gain
During this second phase, they noted the significant difference mP-CR had on weight gain, with the mP-CR group regaining less than 1% of their body weight. The HH group gaining ten times as much, up by 6.1%.
“Our finding that mP-CR significantly attenuated increases in body weight and TBF [total body fat] and ABF [abdominal body fat] compared to HH despite similar maintenance in [resting metabolic rate] following WM, may imply that P-CR has an additional ‘metabolic advantage’ in preventing weight relapse,” wrote the authors.
“Indeed, previous research from our laboratory confirms the metabolic and body composition advantages of protein-pacing in obese subjects, possibly due to the increased amount and timing of protein intake in the P-CR diet compared to traditional HH (lower protein component),” they added.
They also found that during WM, insulin and glucose levels for all participants remained unchanged.
“This was somewhat surprising given the significant regain of body weight and TBF in HH participants and implies some other mechanisms are responsible for mediating insulin and glucose levels.”
During the initial phase, subjects followed a P-CR regime for six days, with intermittent fasting on the seventh. During P-CR days, participants consumed six meals, in aggregate containing 30% protein, 45% carbohydrate and 25% fat, and providing around 1200 kcals for women and 1500 kcals for men.
On intermittent fast days, participants consumed around 350-400 kcals in total.
Participants also received a daily micronutrient supplement pack, containing a “combination of minerals and vitamins, phytonutrients/antioxidants, and essential fatty acids along with a nutrient-rich herbal tonic”.
During the 52-week WM phase, participants selected either a mP-CR or a HH regime. The mP-CR regime followed a similar diet to the one provided in the weight-loss phase, with two meal replacements (either a shake or a bar) per day, and fasting once or twice a month.
“The HH group observed the dietary guidelines that are in compliance with the [US] National Cholesterol Education Programme Therapeutic Lifestyle Changes (TLC) diet (i.e., <35% of kcal as fat; 50%–60% of kcal as carbohydrates; <200 mg/dL of dietary cholesterol; and 20–30 g/day of fibre). The HH subjects were provided a monthly food stipend to assist in complying with the TLC diet plan,” wrote the authors.
The researchers noted that more (nine out of 19) mP-CR participants dropped out of the WM phase compared to HH participants (four of 18).
They also noted that their intervention likely affected abnormal metabolic status, and suggested both of these required further study and investigation.
Published online ahead of print, doi: 10.3390/nu8080476
“Protein-Pacing Caloric-Restriction Enhances Body Composition Similarly in Obese Men and Women during Weight Loss and Sustains Efficacy during Long-Term Weight Maintenance”
Authors: Arciero, P J, et al