Gastrointestinal delivery of bitter hop extract reduces appetite and food cravings in healthy adult women undergoing acute fasting

Abstract

Background: Dietary restrictions or reductions such as fasting for weight loss are often difficult to adhere to due to increased appetite and food cravings. Recently, gastrointestinal delivery of bitter hops has been shown to be effective at reducing appetite in men. Our aim was to determine the effect of a bitter hop extract on appetite and cravings in women, using a 24 h, water-only fast.

Methods: This was a randomized, double-blind, cross-over treatment study. Thirty adult women were recruited and required to fast for 24 h from 1800 h to 1800 h on three occasions and given an ad libitum meal to break each fast. Treatments of either a placebo or one of two doses (high dose; HD: 250 mg or low dose; LD: 125 mg) of a bitter hop-based appetite suppressant (Amarasate®) were given twice per day at 16 and 20 h into the fast.

Results: The HD and LD treatment groups exhibited a significant (p < 0.05) reduction in appetite and cravings for food when compared to the placebo control. Two participants reported loose stools and one reported heartburn while on the HD treatment, and one participant reported loose stools while on the LD treatment.

Conclusion: These data suggest that appetite suppressant co-therapy may be useful in reducing hunger during fasting in women and shows that gastrointestinal delivery of bitter compounds may also be an effective method of reducing cravings for food.This trial received ethical approval from the Northen B New Zealand Human Disability and Ethics committee (Northern B Health and Disability Ethics Committee (2022 EXP 10995) and was prospectively registered with the Australian New Zealand Clinical Trial Registry (ACTRN12622000107729).

Keywords: Appetite; Bitter taste receptors; Dietary supplement; Fasting; Satiety; Water fasting.

Graphical abstract

Fig. 1

Consolidated Standards of Reporting Trials (CONSORT) flow diagram of the recruitment, enrollment, and random assignment process. HD (High Dose — 500 mg Amarasate®), LD (Low Dose — 250 mg Amarasate).

Fig. 2

Study protocol on days 1–3. At 16 h into the 24 h fast (t = 0 min) participants recorded their baseline Visual Analogue Scale (VAS)-based appetite assessments and then consumed a delayed digestion capsule containing either a placebo, a low-dose Amarasate® hop extract or a high-dose Amarasate hop extract. Every 30 min, VAS-based appetite assessment questionnaires were taken from 16 h until 24 h into the 24 h fast. Then at 20 h into the 24 h fast (t = 240 min) a second treatment capsule matched to the first was given.

Fig. 3

Visual analogue scale (VAS) results for hunger and fullness throughout the day in response to placebo, low dose (LD) and high dose (HD) Amarasate® treatments. Changes (Δ) in the ratings of (a) hunger and (c) fullness. Histograms show AUCΔ0–510 min for Δ with respect to (b) hunger and (d) fullness. Values are means ± standard error of the means (SEMs); n = 27. Treatment capsules were administered at t = 0 min and t = 240 min. Hunger and fullness exhibited a significant main effect for treatment p < 0.05 with evidence for a significant treatment × time interaction for hunger p ​< ​0.05. Pairwise comparisons: HD vs PLACEBO, ∗p < 0.05, LD vs PLACEBO, ˄ p < 0.05.

Fig. 4

Visual analogue scale (VAS) results for satisfaction and thoughts of food (TOF) throughout the day in response to placebo, low dose (LD) and high dose (HD) Amarasate® treatments. Changes (Δ) in the ratings of (a) satisfaction and (c) TOF. Histograms show AUCΔ0–510 min for Δ with respect to (b) satisfaction and (d) TOF. Values are means ± standard error of the means (SEMs); n = 27. Treatment capsules were administered at t = 0 min and t = 240 min. Satisfaction showed evidence for a main treatment effect (p < 0.05) and whereas TOF did not.

Fig. 5

Visual analogue scale (VAS) results for cravings for food and cravings for sugary food throughout the day in response to placebo, low dose (LD) and high dose (HD) Amarasate® treatments. Changes (Δ) in the ratings of (a) cravings for food and (c) cravings for sugary food. Histograms show AUCΔ0–510 min for Δ with respect to (a) cravings for food and (c) cravings for sugary food. Values are means ± standard error of the means (SEMs); n = 27. Treatment capsules were administered at t = 0 min and t = 240 min. Cravings for food exhibited a significant main effect for treatment p ​< ​0.05. Pairwise comparisons: HD vs PLACEBO, ∗p < 0.05, LD vs PLACEBO, ˄ p < 0.05.

Fig. 6

Visual analogue scale (VAS) results for cravings for fatty food and cravings for savory food throughout the day in response to placebo, low dose (LD) and high dose (HD) Amarasate® treatments. Changes (Δ) in the ratings of cravings for fatty food (a) and cravings for savory food (c). Histograms show AUCΔ0–510 min for Δ with respect to cravings for fatty food (a) and cravings for savory food (c). Values are means ± standard error of the means (SEMs); n = 27. Treatment capsules were administered at t = 0 min and t = 240 min. Cravings for savory food exhibited significant main effect for treatment p ​< ​0.05. Pairwise comparisons: HD vs PLACEBO, ∗p < 0.05, LD vs PLACEBO, ˄ p < 0.05.