Scientific papers and research data cited in our articles
E01 🧠 Brain & Mental 2015
Chewing Maintains Hippocampus-Dependent Cognitive Function
Chen H, Iinuma M, Onozuka M, Kubo KY.
PMC / International Journal of Medical Sciences
📝 Summary
A review article, not new experimental work by the authors. It summarises mainly rodent studies showing that sensory input from chewing projects via the trigeminal nerve to the reticular formation, thalamus, cortex and hippocampus; that molar extraction or a soft diet was associated with lower CA1/CA3 neuron density and poorer spatial memory; and that chewing under restraint stress prevented suppression of dentate gyrus cell proliferation and lowered plasma corticosterone. All of these are animal findings and do not demonstrate an effect in humans.
🔑 Key Findings
▸A review, not the authors' own experiments
▸In animals, reduced chewing was linked to hippocampal neuron loss and poorer spatial memory
▸In animals, chewing under stress lowered corticosterone (unverified in humans)
Effects of Mastication Dynamics on GLP-1 Secretion in Mice
菅 悠希（北海道医療大学大学院歯学研究科）
北海道医療大学学術リポジトリ（学位論文）
📝 Summary
A doctoral thesis (not a peer-reviewed journal article) using 190 male C57BL/6J mice. Active GLP-1 30 minutes after intake was significantly higher in the solid-feed (chewing) group than the liquid-feed group (n=10 each, p<0.05). The difference disappeared under pharmacological vagal blockade and with calorie-free feed. In the acute experiment, insulin secretion showed no significant difference under any condition. In the 12-week feeding experiment, however, fasting active GLP-1 and fasting insulin were both significantly higher in the long-term chewing group (MWU, p<0.05), and pancreatic β-cell area was also significantly larger. Body weight, blood glucose, and the oral glucose tolerance test showed no significant difference between groups. The author states that chewing itself did not affect insulin secretion, but a chewing habit did. These are mouse findings, not human evidence.
🔑 Key Findings
▸Mouse study: active GLP-1 significantly higher 30 min after intake (p<0.05)
▸The difference disappeared under vagal blockade
▸No acute difference in insulin, but fasting insulin was significantly higher after 12 weeks of chewing
A randomized crossover trial in 11 healthy young men comparing a 200 kcal liquid meal swallowed directly, held in the mouth for 30 seconds, or chewed for 30 seconds per sip. Diet-induced thermogenesis over 90 minutes rose from 3.4 to 5.6 to 7.4 kcal (p < 0.05). The difference is about 4 kcal, and more than half of the increase is explained by the tasting condition alone. Celiac artery blood flow rose significantly with both tasting and chewing, but chewing did not exceed tasting (5.5 vs 5.9 L), and the superior mesenteric artery showed no difference. Brown adipose tissue was not measured, and there were no significant differences in hunger, fullness, or respiratory exchange ratio.
🔑 Key Findings
▸Postprandial DIT increased significantly (about 4 kcal)
▸More than half of the increase came from tasting alone
▸Celiac artery blood flow rose, but chewing did not exceed tasting
▸Body weight and fat were not measured; the authors only speculate
A Suita Study follow-up of 599 middle-aged men. Low masticatory ability was independently associated with metabolic syndrome, hypertension, high triglycerides and fasting hyperglycaemia. This is an observational study: it does not establish that poor chewing causes these conditions, and the sample is limited to middle-aged men.
🔑 Key Findings
▸Low masticatory ability independently associated with metabolic syndrome
▸Correlated with hypertension and high triglycerides
Mastication of Nuts under Realistic Eating Conditions: Energy Balance
McArthur BM, Considine RV, Mattes RD.
Nutrients (MDPI)
📝 Summary
A within-subject crossover trial in 50 healthy adults (25 men, 25 women) comparing 28 g of whole walnuts with the same amount as walnut butter. Fullness was higher and hunger lower with whole nuts (p < 0.05), but glucose, insulin, and active GLP-1 showed no significant differences, so hormones do not explain the satiety difference. The authors raise a neural pathway as a possibility without testing it. Faecal energy loss was not measured in this study. **The magnitudes of the appetite ratings are not given numerically in the text — only p-values and a figure — so the size of the effect cannot be read from the paper.** Eligibility required healthy dentition, so people with dental problems or difficulty chewing were excluded from the outset. **One author received a research grant from the California Walnut Commission to conduct the study.**
🔑 Key Findings
▸Whole nuts produced higher fullness and lower hunger (p < 0.05)
▸No significant differences in glucose, insulin, or active GLP-1
▸Desire for sweets was lower with the butter, the opposite direction
▸The mechanism behind the satiety difference remains unidentified
Chewing and Its Influence on Swallowing, GI, and Nutrition: A Systematic Review
Kumar A, Almotairy N, Merzo JJ, et al.
Critical Reviews in Food Science and Nutrition
📝 Summary
A systematic review by Kumar et al., not new experimental work. It surveys existing research on how chewing affects swallowing, gastrointestinal physiology and nutrition-related factors: the topics it covers include how poorly chewed boluses behave in the gut and the glycaemic response, and whether reduced masticatory function is associated with narrower food choices and shifts in gut microbiota. **What the review concluded on each of these is not stated in the abstract, and we have not read the full text, so we cannot report it.** Most of the individual studies included are small intervention or observational studies. **Seventy-one studies were included; 46 supported the hypothesis and 25 refuted it (64.7% supporting).** The authors' own GRADE assessment rates the certainty of evidence that chewing is an important contributor to swallowing and to gastrointestinal physiology as **low to very low**, and its contribution to nutrition-related parameters as **moderate to very low**. The authors state that robust studies with proper design, adequate sample size and well-defined outcome parameters are needed before conclusive evidence can be established. **This is the most frequently cited source on this site, and that is the level of certainty behind it.** We have confirmed the abstract only; funding and conflicts of interest are unverified.
🔑 Key Findings
▸A systematic review, not the authors' own experiments
▸An association between insufficient chewing and postprandial glucose response is reported
▸Most included studies are small
▸25 of the 71 studies did not support the hypothesis (46 did, 64.7%)
▸The authors grade the certainty as low to very low for swallowing and the gut, moderate to very low for nutrition
Masticatory Function and Hypertension: A Cross-Sectional NHANES Study
Guo H, Yang H, Li J, Lv T.
Medicine (Baltimore)
📝 Summary
A cross-sectional observational study using NHANES 2005-2018 data on 25,638 non-institutionalised adults. Masticatory function was assessed by functional tooth units (FTU); the optimal group (FTU 10-12) had an adjusted odds ratio for hypertension of 0.82 (95% CI 0.72-0.92) compared with the impaired group (FTU below 3). Mediation analysis attributed 18.0% (95% CI 14.8-21.1) of the association to HbA1c. The authors state explicitly that the cross-sectional design does not permit causal inference.
🔑 Key Findings
▸Cross-sectional study (n=25,638): inverse association with hypertension (adjusted OR 0.82)
▸HbA1c statistically accounted for 18.0% of the association
▸The authors state that causal inference is not possible
Autonomic Nervous System Balance and Erectile Dysfunction
Xu J, Chen Y, Gu L, et al.
Frontiers in Endocrinology
📝 Summary
A cross-sectional comparison of 75 men with psychogenic erectile dysfunction and 75 healthy men (150 total, mean age 31.9 years). Patients had significantly higher perceived stress, a significantly higher LF/HF ratio (p=0.014), and significantly lower HF and pNN50 (both p<0.001). Despite the HPA axis in the title, none of the cortisol measures differed significantly between groups (CAR AUCi p=0.744, CAR AUCg p=0.972, diurnal AUCg p=0.970, DCS p=0.784); the authors conclude that the stress response in these patients is characterised by autonomic imbalance rather than HPA dysregulation. This paper does not mention chewing at all. A previous version of this entry claimed that rhythmic chewing suppresses HPA axis overactivity; that sentence does not appear in the source and has been removed.
🔑 Key Findings
▸Cross-sectional (n=150): higher LF/HF, lower HF and pNN50 in patients
▸Cross-sectional design does not establish direction of causation
▸Cortisol measures did not differ; the authors attribute this to autonomic imbalance, not HPA dysregulation
Erectile Dysfunction: Definition and Pathophysiology
Johns Hopkins Medicine（患者向け解説ページ）
Johns Hopkins Medicine（査読論文ではない）
📝 Summary
A patient-education page published by Johns Hopkins Medicine, not a peer-reviewed article. It presents erectile dysfunction as a sentinel marker for cardiovascular and metabolic disease and lists the main risk factors for organic ED (obesity, insulin resistance, diabetes, atherosclerosis, hypertension). It makes no mention of chewing.
🔑 Key Findings
▸A hospital patient-education page, not a peer-reviewed article
▸ED is presented as an early marker of cardiovascular disease
Irwin Goldstein（Boston University Sexual Medicine）
BU Sexual Medicine（査読論文ではない）
📝 Summary
An explanatory page published by Boston University Sexual Medicine, not a peer-reviewed article. It explains that initiating and maintaining an erection requires parasympathetic dominance and nitric-oxide-mediated smooth muscle relaxation, that sympathetic activation works against erection, and that nocturnal erections during REM sleep occur when sympathetic activity switches off. It makes no mention of chewing.
🔑 Key Findings
▸A university explanatory page, not a peer-reviewed article
An explanatory article written for a public-relations magazine of the Agriculture & Livestock Industries Corporation by an employee of the Kamukoto research division of Lotte, a gum manufacturer. It is not a peer-reviewed paper and carries a conflict of interest. Reported effects (raised salivary S-IgA, increased scalp blood flow, changes in jawline angle) are drawn mainly from small, open-label studies by the author or the same company. Note that improvements in bite force and sprint start in female junior-high students over one month (Kanno et al. 2020) and improvements in maths scores over 14 weeks (Johnston et al. 2012) come from two separate studies; an earlier version of this entry described them as a single intervention.
🔑 Key Findings
▸Not peer-reviewed: an explanatory article by a gum manufacturer's employee (conflict of interest)
▸The bite-force/sprint result and the maths-score result come from two different studies
▸Most cited work consists of small open-label studies by the author or the same company
Koyama T, Kobayashi K, Hama T, Murakami K, Ogawa R.
PMC / ePlasty
📝 Summary
A massage device (170rpm) applied to one side of the temporal scalp for 4 min/day over 24 weeks increased hair thickness from 0.085 to 0.092mm in 9 healthy men. There was no independent control group; the untreated contralateral scalp of the same participant served as the control. Separately, mechanically stretched cultured human dermal papilla cells showed changes in hair growth-related gene expression and reduced IL6 (an in vitro result, not measured in the participants).
🔑 Key Findings
▸24 weeks of device massage on the temporal scalp significantly increased hair diameter
▸Control was the contralateral scalp of the same person, not an independent group
▸Gene expression and IL6 findings come from cultured cells
Integrative Approach to Hair Growth Cycle and Hair Loss
Natarelli N, Gahoonia N, Sivamani RK.
Journal of Clinical Medicine (MDPI)
📝 Summary
A review article summarizing the hair growth cycle and mechanisms of hair loss; the authors did not conduct new experiments. Blood supply to the deep dermis is involved in angiogenesis and cell division during the growth phase. Androgenetic alopecia involves DHT and other hormonal factors. This source does not address chewing or the temporalis muscle.
🔑 Key Findings
▸Scalp blood flow is involved in hair matrix cell division
▸Androgenetic alopecia involves DHT and other hormonal factors
Mastication and Obesity in Adults: A Systematic Review
Tada A, Miura H.
BMC Oral Health
📝 Summary
A systematic review of 18 studies published between 2007 and 2016 (16 cross-sectional, 1 cohort, 1 RCT). Twelve of the 16 cross-sectional studies reported an association between reduced masticatory function and obesity, and the single RCT (an 8-week gum-chewing intervention, E28) found a within-group reduction in waist circumference, but no significant between-group difference, and virtually no change in weight or BMI in either group; the review authors themselves note that a significant effect may not be obtainable from gum-chewing alone. The authors conclude that because most included studies are cross-sectional, causality has not been established and further RCTs are needed.
🔑 Key Findings
▸Systematic review of 18 studies, mostly cross-sectional, linking reduced chewing to obesity
▸The single RCT (8-week gum chewing) showed a within-group waist reduction only; no between-group difference and no weight or BMI change
▸The authors state that causality is unproven and further RCTs are needed
A large cohort study of 31,742 men aged over 50 (Health Professionals Follow-up Study). Higher physical activity and a healthy BMI were strongly associated with maintained erectile function. The paper does not discuss GLP-1, HbA1c or chewing. A previous version of this entry claimed that improved masticatory function indirectly strengthens these protective factors; that sentence does not appear in the source and has been removed.
🔑 Key Findings
▸A large cohort study of 31,742 men
▸Physical activity and healthy BMI were associated with maintained erectile function
▸The source makes no mention of GLP-1, HbA1c or chewing
Cerebral Blood Flow During Chewing and Cognition in Prognathism Patients
Inagawa Y, Kanzaki H, Kariya C, et al.
Scientific Reports（パイロット研究）
📝 Summary
A pilot study (so described in the paper title) comparing patients with mandibular prognathism to healthy controls. Cerebral blood flow during chewing (fNIRS) in the inferior frontal gyrus was significantly lower in patients than in controls (n=17); median values fell from 57% to 23% on the right and from 50% to 33% on the left. Overall cognitive scores (eye-tracking; 59 controls vs 44 patients, mean age around 25) did not differ significantly (p=0.48). Within the patient group, chewing-related blood flow correlated positively with cognitive scores. The figure of a 30-50% drop in chewing efficiency is quoted from earlier work, not measured here, and the authors make no claim about future dementia risk.
🔑 Key Findings
▸A pilot study: chewing-related blood flow was significantly lower in patients (roughly 40-66% of controls, depending on side)
▸Overall cognitive scores did not differ significantly (p=0.48)
▸Participants averaged about 25 years old; the authors make no claim about dementia risk
Thirty Chews per Bite and GLP-1 Secretion in Healthy Volunteers and Type 2 Diabetics
Sonoki K, Iwase M, Takata Y, et al.
Endocrine Journal 60(3):311-319
📝 Summary
A small study the authors themselves describe as a pilot trial. Thirty healthy volunteers were split into three groups of ten; each compared their usual eating with one assigned style — unilateral chewing, quick eating, or thirty chews per bite (not a full crossover in which everyone did every condition). A standardised 460 kcal meal was used. Only the thirty-chews condition significantly raised active GLP-1 at 30 minutes (9.9±3.3 vs 8.6±2.1 pmol/L, p<0.05), along with its IAUC; unilateral chewing and quick eating showed no significant difference. **Blood glucose and insulin did not change under any condition.** In fifteen patients with type 2 diabetes (mean age 65.9), thirty chews per bite produced no difference in GLP-1 compared with usual eating. The authors note the small pilot sample as a limitation, and that active GLP-1 was measured without an extraction step, so baseline values may be inflated. Funded by a Kyushu Dental University grant; the authors declare no conflict of interest.
🔑 Key Findings
▸In healthy volunteers, thirty chews per bite significantly raised active GLP-1 (p<0.05)
▸Glucose and insulin did not change under any condition
▸No significant effect in patients with type 2 diabetes
▸A small study the authors describe as a pilot trial
More Chewing Reduces Energy Intake in One Meal in Obese and Lean Young Men
Li J, Zhang N, Hu L, et al.
American Journal of Clinical Nutrition 94(3):709-716
📝 Summary
A trial in 30 young Chinese men (16 lean, 14 obese) comparing 15 chews per bite with 40 chews per bite, where a bite was defined as 10 g of food, so bite size as well as chew count was held constant. With 40 chews, participants ingested 11.9% less energy, and plasma ghrelin was lower while GLP-1 and CCK were higher; the abstract puts this as "regardless of status", meaning overall rather than 11.9% within each group. **The 2200 kJ test meal in the abstract was eaten under both conditions to measure gut hormones, and the abstract does not make clear which meal the 11.9% difference was measured on.** **This site has not been able to read the full text (paywalled).** The above is what the abstract supports; the exact significance levels, whether the order was randomised, the authors' stated limitations, and the funding source have not been verified. Participants were male only.
🔑 Key Findings
▸Forty chews per bite led to 11.9% less energy intake than fifteen
▸Ghrelin was reported lower, with GLP-1 and CCK higher
▸This site has not read the full text; significance levels and funding are unverified
Gum Chewing While Fasting and Blood GLP-1 in Healthy Non-Obese Men
Xu J, Xiao X, Li Y, et al.
Endocrine 50(1):93-98
📝 Summary
A within-subject crossover trial in 12 healthy non-obese men. While fasting, participants chewed sugarless gum at 80 chews per 2 minutes for 30 minutes on one day and did not chew on another day, three days apart. GLP-1 at 30 minutes was significantly higher in the chewing condition (49.6±20.3 vs 38.9±20.9 pmol/L, p=0.031), and satiety was higher at 15, 25 and 30 minutes (p=0.043, p=0.014 and p=0.018 respectively). **Glucose, insulin, GIP and hunger showed no significant differences.** The authors phrase their conclusion not as "increases GLP-1" but as reducing the decline in GLP-1 that occurs while fasting. They list limited blood sample volume and not measuring other gut hormones as limitations. Funded by the National Natural Science Foundation of China, not by industry. The sample is small at 12, and male only.
🔑 Key Findings
▸Gum chewing while fasting gave significantly higher GLP-1 at 30 minutes (p=0.031)
▸No significant differences in glucose, insulin or GIP
▸The authors describe it as reducing a decline, not as increasing GLP-1
Vegetable Consumption With Chewing and Postprandial Glucose Metabolism in Healthy Young Men (RCT)
Kamemoto K, Tataka Y, Hiratsu A, et al.
Scientific Reports 14:7557
📝 Summary
A randomised crossover trial in 19 healthy young men. Participants ate shredded cabbage while chewing to a metronome on one day, and the same amount of cabbage pureed and swallowed without chewing on another, each followed by an identical energy jelly, with 180 minutes of follow-up. Total GLP-1 was higher in the chewing condition at 45 (p=0.002), 60 (p=0.017) and 90 minutes (p=0.049), and the incremental areas under the curve for insulin and GIP were also higher (p=0.019 and p=0.009). **However, this trial also produced results that do not support chewing.** GLP-1 was significantly *lower* in the chewing condition at 120 (p=0.027) and 180 minutes (p=0.023), and the overall GLP-1 area under the curve did not differ. Glucose showed no difference in area under the curve, and at 30 minutes it was actually higher in the chewing condition (p=0.007). Appetite and energy intake were not measured. **The study was funded by Kewpie Corporation (Tokyo), and 3 of the 9 authors are employees of that company.** A fourth author discloses having received funding from it. The authors list as limitations the small sample of healthy young men only, that habitual chew counts were not recorded, and that using a jelly as the test meal limits generalisation to solid mixed meals. Note that what was compared is food form (shredded versus pureed), not the number of chews — the same design as E05.
🔑 Key Findings
▸GLP-1 was higher when chewing at 45, 60 and 90 minutes, as were the insulin and GIP areas under the curve
▸But GLP-1 was lower at 120 and 180 minutes, and the overall GLP-1 area under the curve did not differ
▸Glucose was actually higher in the chewing condition at 30 minutes (p=0.007)
▸Funded by Kewpie Corporation, with 3 of 9 authors employed by the company
▸What was compared is food form, not the number of chews
Tooth Loss and Nutritional Status: An Overview of Systematic Reviews
Kaurani P, Kakodkar P, Bhowmick A, Samra RK, Bansal V.
BMC Oral Health 24(1):838
📝 Summary
An overview of systematic reviews — not the authors’ own experiments. Seven systematic reviews (three with meta-analysis) were selected from 1,525 records. Two meta-analyses found that fully or partially edentulous people were more likely to be malnourished or at risk of malnutrition (RR = 1.095, 95% CI 1.007–1.190, p = 0.033; RR = 1.22, 95% CI 1.11–1.32, p < 0.01). **A third found no association between edentulism and malnutrition (RR = 1.072, 95% CI 0.9657–1.200).** AMSTAR 2 rated four of the seven as high quality, one as low and **two as critically low**, and the authors conclude that confidence in the available evidence is low. **The exposure is the number of teeth, not masticatory efficiency, and reviews of prosthetic interventions were excluded from the outset.** The authors received no funding and declare no competing interests.
🔑 Key Findings
▸An overview of reviews, not new experimental work
▸Two meta-analyses found an association with malnutrition, one found none
▸Two of the seven included reviews were rated critically low quality
▸The exposure is the number of teeth, not masticatory efficiency
▸Reviews of prosthetic interventions were excluded
Texture-Modified Foods and Thickened Liquids for Adults with Oropharyngeal Dysphagia (Second Guideline Update)
Hansen T, Beck AM, Kjaersgaard A, Poulsen I.
Clinical Nutrition ESPEN 49:551-555
📝 Summary
A systematic review (PRISMA, Cochrane risk-of-bias 2, GRADE) of thickening agents and texture-modified diets in adults over 17 with oropharyngeal dysphagia. Searching PubMed, Embase, CINAHL, the Cochrane Database of Systematic Reviews and CENTRAL from 1 January 2015 to 19 May 2021 yielded **only one newly eligible study**, giving three RCTs in total — two of which were already in the previous guideline. **All three concern the thickening of liquids; none is an RCT of texture-modified food itself.** The authors conclude there is no convincing evidence that thickened liquid or texture-modified diet prevents death or pneumonia, or improves quality of life, nutritional status or oral intake, and the earlier **weak recommendation against** thickening liquids was left unchanged. **This means not proven, not disproven.** We have only been able to read the abstract, not the full text.
🔑 Key Findings
▸Six years across five databases yielded only one newly eligible study
▸All three RCTs concern thickened liquids, not texture-modified food itself
▸No convincing evidence for death, pneumonia, quality of life, nutrition or oral intake
▸The weak recommendation against thickening liquids was unchanged
Eating Speed and Metabolic Syndrome: A Systematic Review and Meta-Analysis
Yuan SQ, Liu YM, Liang W, et al.
Frontiers in Nutrition 8:700936
📝 Summary
A meta-analysis of 29 studies and 465,155 participants. Compared with slow eaters, fast eaters had higher odds of metabolic syndrome (OR 1.54, 95% CI 1.27–1.86), central obesity (1.54, 1.37–1.73), elevated blood pressure (1.26, 1.13–1.40), low HDL (1.23, 1.15–1.31), elevated triglycerides (1.29, 1.18–1.42) and elevated fasting glucose (1.16, 1.06–1.27). **However, 20 of the 29 studies are cross-sectional (7 cohort, 1 RCT, 1 case-control), so causality is not established.** **The exposure is always self-reported eating speed from questionnaires — no common standard, and not a measurement of chewing.** Only 16 of 29 used a validated instrument; 16 of 29 were Japanese and only 4 were non-Asian. Publication bias was detected for central obesity. **Five of the 29 studies were in children aged 6–18, so this is not an adults-only analysis.** Funded by public grants including the National Natural Science Foundation of China; the authors declare no conflict of interest.
🔑 Key Findings
▸Metabolic syndrome: OR 1.54 (95% CI 1.27–1.86)
▸Fasting hyperglycaemia shows the smallest association, OR 1.16 (1.06–1.27)
▸20 of 29 studies are cross-sectional; causality is not established
▸The exposure is self-reported eating speed, not measured chewing
▸Publication bias was detected for central obesity
Experimentally Manipulated Eating Rate, Energy Intake and Hunger: A Systematic Review and Meta-Analysis
Robinson E, Almiron-Roig E, Rutters F, et al.
American Journal of Clinical Nutrition 100(1):123-151
📝 Summary
A meta-analysis restricted to studies that **experimentally manipulated eating rate** (22 studies), not observational data. Slower eating was associated with lower energy intake at that meal (SMD 0.45, 95% CI 0.25–0.65, p < 0.0001), consistently across types of manipulation (chewing instructions, pacing devices) though with large heterogeneity. **There was no significant relation between eating rate and hunger either at the end of the meal or up to 3.5 hours later.** So the finding is "less is eaten at that meal", not "people feel fuller". **All of these are single-meal laboratory manipulations; none measured weight change.** Funded by the UK Medical Research Council, **though one author is affiliated with the Nestlé Research Centre and another with Top Institute Food and Nutrition.** We have only the abstract and the affiliation list, not the full text.
🔑 Key Findings
▸Slower eating lowered energy intake at that meal (SMD 0.45, p < 0.0001)
▸Consistent across manipulation types, but heterogeneity is large
▸No significant relation between eating rate and hunger
▸Single-meal laboratory manipulations; weight was not measured
▸One author is affiliated with the Nestlé Research Centre
Increasing the Number of Chews before Swallowing Reduces Meal Size in Normal-Weight, Overweight, and Obese Adults
Zhu Y, Hollis JH.
Journal of the Academy of Nutrition and Dietetics 114(6):926-931
📝 Summary
A randomised crossover trial in 45 normal-weight, overweight and obese adults aged 18–45. **Rather than prescribing a fixed count, each participant’s habitual number of chews was measured first, then set to 100%, 150% or 200% of it.** Participants ate pizza until comfortably full. Compared with 100%, intake fell by **9.5% at 150% and 14.8% at 200%**; meal duration lengthened and eating rate slowed. **Subjective appetite at meal termination and over the following 60 minutes did not differ**, so the reduction cannot be attributed to feeling less hungry. **This is a single-meal study; weight was not measured.** Participants were community residents in Ames, Iowa. We have only the abstract; funding and conflicts of interest are unverified.
🔑 Key Findings
▸Intake fell 9.5% at 150% and 14.8% at 200% of habitual chews
▸This manipulates chew count itself, not food form
Increased Chewing Reduces Energy Intake, but Not Postprandial Glucose and Insulin
Borvornparadorn M, Sapampai V, Champakerdsap C, Kurupakorn W, Sapwarobol S.
Nutrition & Dietetics 76(1):89-94
📝 Summary
A randomised crossover trial in 41 participants of healthy weight and overweight. Phase I measured habitual bite size and chewing frequency; Phase II compared **15 versus 50 chews per bite**. Overweight participants chewed less and consumed more energy. **At 50 chews, energy intake fell regardless of BMI.** **Insulin did not differ significantly by chew count at any time point (0, 30, 60, 90, 120, 180 minutes).** The abstract notes an "insignificant" rise in insulin at 50 chews — that is a non-significant change. **For glucose the abstract gives no time-by-time result; the null comes from the title and the concluding sentence that chewing did not affect postprandial glucose or insulin.** **The abstract gives no numeric magnitude for the intake reduction, so the effect size cannot be read from it.** We have only the abstract; funding and conflicts of interest are unverified.
🔑 Key Findings
▸At 50 chews per bite, energy intake fell regardless of BMI
▸Neither glucose nor insulin changed significantly at any time point
▸Overweight participants chewed less and ate more
▸The abstract gives no magnitude, so effect size cannot be read
More Chews During a Fixed-Amount Meal Suppress Postprandial Appetite and Modulate Glycaemic Response in Older Males
Zhu Y, Hsu WH, Hollis JH.
Physiology & Behavior 133:136-140
📝 Summary
A randomised crossover trial in **15 men aged 65 or over**. A fixed-amount meal (2050 kJ) was eaten at **15 versus 40 chews per bite**, with 3 hours of follow-up. At 40 chews, postprandial hunger (p = 0.003), preoccupation with food (p < 0.001) and desire to eat (p < 0.001) were all significantly lower. **Glucose, insulin and GIP were significantly higher at meal completion with 40 chews (all p < 0.01) and significantly lower during the late postprandial period (all p < 0.05)** — whether they rose or fell depends on when you measure. Intake at an ad libitum meal 3 hours later did not differ. **Fixing the meal size lets appetite be observed separately from how much was eaten.** The sample is 15 men only, and the authors note that the contribution to long-term energy balance remains to be investigated. We have only the abstract; funding and conflicts of interest are unverified.
🔑 Key Findings
▸One of the few interventions in older adults on this site: 15 men aged 65+
▸At 40 chews, postprandial hunger, preoccupation with food and desire to eat all fell
▸Glucose, insulin and GIP were higher at meal end and lower later
▸Intake at an ad libitum meal 3 hours later did not differ
Randomized Controlled Trial of Chewing Gum for Weight Loss
Shikany JM, Thomas AS, McCubrey RO, Beasley TM, Allison DB.
Obesity (Silver Spring) 20(3):547-552
📝 Summary
An 8-week randomised controlled trial in **201 overweight and obese adults**. The intervention group (n = 102) received printed nutrition information plus **at least 90 minutes of gum chewing per day**; the control group (n = 99) received the printed information only. **Body weight was the primary outcome.** Adherence to the gum protocol exceeded 95%, but **in the intention-to-treat analysis there were virtually no changes in weight or BMI in either group.** Waist circumference fell significantly within the intervention group (mean -1.4 ± 5.3 cm, p = 0.0128), but **there was no significant between-group difference in change.** Systolic and diastolic blood pressure likewise fell within the intervention group but showed **no between-group difference**. Completers-only analyses gave essentially the same results. The authors conclude that eight weeks of regular gum chewing did not facilitate weight loss in these adults. **This is the only RCT on this site in which a chewing intervention measured body weight as its primary outcome, and the answer was that it did not move.** It is the single RCT cited by the E14 systematic review. We have confirmed the abstract only; funding and conflicts of interest are unverified.
🔑 Key Findings
▸n = 201 over 8 weeks: the only RCT here with body weight as the primary outcome of a chewing intervention
▸Weight and BMI barely changed in either group in the intention-to-treat analysis
▸Waist circumference fell within the intervention group but showed no between-group difference
▸Blood pressure likewise showed no between-group difference
▸The authors conclude it did not facilitate weight loss