Viscous placebo and carbohydrate breakfasts similarly decrease appetite and increase resistance exercise performance compared with a control breakfast in trained males

Abstract

Given the common view that pre-exercise nutrition/breakfast is important for performance, the present study investigated whether breakfast influences resistance exercise performance via a physiological or psychological effect. Twenty-two resistance-trained, breakfast-consuming men completed three experimental trials, consuming water-only (WAT), or semi-solid breakfasts containing 0 g/kg (PLA) or 1·5 g/kg (CHO) maltodextrin. PLA and CHO meals contained xanthan gum and low-energy flavouring (approximately 122 kJ), and subjects were told both ‘contained energy’. At 2 h post-meal, subjects completed four sets of back squat and bench press to failure at 90 % ten repetition maximum. Blood samples were taken pre-meal, 45 min and 105 min post-meal to measure serum/plasma glucose, insulin, ghrelin, glucagon-like peptide-1 and peptide tyrosine-tyrosine concentrations. Subjective hunger/fullness was also measured. Total back squat repetitions were greater in CHO (44 (sd 10) repetitions) and PLA (43 (sd 10) repetitions) than WAT (38 (sd 10) repetitions; P < 0·001). Total bench press repetitions were similar between trials (WAT 37 (sd 7) repetitions; CHO 39 (sd 7) repetitions; PLA 38 (sd 7) repetitions; P = 0·130). Performance was similar between CHO and PLA trials. Hunger was suppressed and fullness increased similarly in PLA and CHO, relative to WAT (P < 0·001). During CHO, plasma glucose was elevated at 45 min (P < 0·05), whilst serum insulin was elevated (P < 0·05) and plasma ghrelin suppressed at 45 and 105 min (P < 0·05). These results suggest that breakfast/pre-exercise nutrition enhances resistance exercise performance via a psychological effect, although a potential mediating role of hunger cannot be discounted.

Effect of Intake of Food Hydrocolloids of Bacterial Origin on the Glycemic Response in Humans: Systematic Review and Narrative Synthesis

“…Figure 2 summarizes the process of literature search, identification, and screening, based on the PRISMA flow chart. Of these 14 papers, 4 investigated pullulan [ 22 , 23 , 24 , 25 ], 7 investigated xanthan gum [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ] and three investigated dextran [ 33 , 34 , 35 ].…”

“…In a recent publication, Naharudin et al [ 32 ] used xanthan gum in three arm-study. The first intervention was water control, and the second intervention a viscous breakfast (eaten with a spoon) based on low-calorie orange squash and xanthan gum.…”

“…There was no significant overall effect on satiety for 2 h test. Naharudin et al [ 32 ] assessed the hunger using VAS reported that xanthan gum lowered hunger and increased fullness compared to control. They concluded that the increased viscosity caused by the xanthan was responsible for the changes in satiety.…”

“…The addition of 2.5 g of xanthan to an acute glucose load drink reduced the area under the curve for glucose [ 28 ]. However, an addition of about 0.5 g to an acute intervention juice drink did not change the area under the curve for glucose [ 29 ] nor in addition to a viscous breakfast [ 32 ].…”

Omission of a carbohydrate‐rich breakfast impairs evening endurance exercise performance despite complete dietary compensation at lunch

“…Carbohydrate-rich breakfast also improves performance during both shorter duration high-intensity endurance exercise (Galloway, Lott, & Toulouse, 2014;Mears et al, 2018), and during resistance exercise (Naharudin et al, 2020(Naharudin et al, , 2019. However, accumulating evidence suggests these effects may be psychological (placebo) rather than physiological in origin (Mears et al, 2018;Naharudin et al, 2020). Irrespective of the potential mechanisms, current evidence indicates that morning or early afternoon exercise performance will be optimised by consuming a carbohydrate-rich meal several hours prior to the event (Clayton & James, 2016).…”