Does a Higher Protein Diet Promote Satiety and Weight Loss Independent of Carbohydrate Content? An 8-Week Low-Energy Diet (LED) Intervention

Abstract

Both higher protein (HP) and lower carbohydrate (LC) diets may promote satiety and enhance body weight (BW) loss. This study investigated whether HP can promote these outcomes independent of carbohydrate (CHO) content. 121 women with obesity (BW: 95.1 ± 13.0 kg, BMI: 35.4 ± 3.9 kg/m2) were randomised to either HP (1.2 g/kg BW) or normal protein (NP, 0.8 g/kg BW) diets, in combination with either LC (28 en%) or normal CHO (NC, 40 en%) diets. A low-energy diet partial diet replacement (LEDpdr) regime was used for 8 weeks, where participants consumed fixed-energy meal replacements plus one ad libitum meal daily. Four-day dietary records showed that daily energy intake (EI) was similar between groups (p = 0.744), but the difference in protein and CHO between groups was lower than expected. Following multiple imputation (completion rate 77%), decrease in mean BW, fat mass (FM) and fat-free mass (FFM) at Week 8 in all was 7.5 ± 0.7 kg (p < 0.001), 5.7 ± 0.5 kg (p < 0.001), and 1.4 ± 0.7 kg (p = 0.054) respectively, but with no significant difference between diet groups. LC (CHO×Week, p < 0.05), but not HP, significantly promoted postprandial satiety during a preload challenge. Improvements in blood biomarkers were unrelated to LEDpdr macronutrient composition. In conclusion, HP did not promote satiety and BW loss compared to NP LEDpdr, irrespective of CHO content.

The importance of fat-free mass and constituent tissue-organs in the control of human appetite

“…An increased motivation to eat following intentional weight loss is thought to be a critical reason for weight regain, but changes in subjective hunger and appetite-related hormones following weight loss are inconsistent [18–20]. These discrepancies may in part relate to the method of energy restriction used, with attenuated compensatory changes in appetite seen following ketogenic and very-low calorie diets for example [21].…”

“…An increased motivation to eat following intentional weight loss is thought to be a critical reason for weight regain, but changes in subjective hunger and appetite-related hormones following weight loss are inconsistent [18][19][20]. These discrepancies Conceptual diagram of the episodic and tonic physiological processes that influence the inhibition and drive to eat.…”

No Evidence That Circulating GLP-1 or PYY Are Associated with Increased Satiety during Low Energy Diet-Induced Weight Loss: Modelling Biomarkers of Appetite

“…BW loss changes body composition and, in turn, physiology, including circulating concentrations of glycemic-related parameters, gastrointestinal (GI) peptides, and amino acids (AAs) [ 12 , 13 , 14 ], several of which have been hypothesised as associated and/or causative of appetite change. GI peptides, such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), have long been proposed to act as “satiety hormones” [ 15 ].…”

“…Additionally, the complicated physiological mechanism of appetite regulation may involve multiple biomarkers, such as circulating glucose and AAs [ 12 , 30 , 31 , 32 ]. Yet, the associations between these biomarkers and appetite have only been investigated under conditions of energy balance in acute postprandial studies.…”

“…Given that we have previously reported a decrease in postprandial hunger when assessed as incremental change relative to fasting baseline in this 8-week LED weight loss study [ 12 ], the primary objective of the current analysis was to investigate whether the decrease in postprandial hunger may be associated with a concurrent increase in circulating GLP-1 and PYY, as previously reported in bariatric and pharmacological studies. This research investigated the association between circulating concentrations of GLP-1, PYY and satiety during diet-induced BW loss, for which a significant positive association has been purported but for which there is little underpinning data.…”