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Research Area: Body Weight/Satiety

Longitudinal analysis of nut-inclusive diets and body mass index among overweight and obese African American women living in rural Alabama and Mississippi, 2011–2013.

Sterling, S.R., B. Bertrand, S. Judd, T.L. Carson, P. Chandler-Laney, M.L. Baskin, 2017. Longitudinal analysis of nut-inclusive diets and body mass index among overweight and obese African American women living in rural Alabama and Mississippi, 2011–2013. Prev Chronic Dis 2017;14:160595. DOI: https://doi.org/10.5888/pcd14.160595.

Introduction: Nuts, when eaten alongside other nutritionally rich foods, may decrease obesity and related chronic disease risks, which are high among African American women in the rural South. We monitored changes in nut intake, other obesity-related foods (fruits, vegetables, red or processed meats, added sugars), and body mass index (BMI) over a 2-year weight loss intervention among 383 overweight and obese African American women in rural Alabama and Mississippi. Methods: Two dietary recalls were administered at 4 points over 24 months. Mann–Whitney tests compared differences in median food group intake between nut consumers and non-nut consumers, and t tests identified BMI differences between groups. Mixed linear models tested the relationship between nut intake and intake of the select food groups, and between nut intake and BMI over time. Results: Overall nut consumers ate more fruits and vegetables and less red meat than non-nut consumers. Nut consumers had lower BMI values than non-nut consumers. Weight loss by the end of the intervention was significant for nut consumers but not for non-nut consumers, even after accounting for kilocalorie consumption and physical activity engagement. Conclusion: Nut consumption is associated with consumption of other nutritionally rich foods and lower BMI among African American women in rural Alabama and Mississippi. Future interventions should target increasing daily nut intake, decreasing added sugar intake, and identifying strategies to encourage positive dietary changes to continue after an intervention.

Intramyocellular triacylglycerol accumulation across weight loss strategies; Sub-study of the CENTRAL trial.

Gepner, Y., I. Shelef, D. Schwarzfuchs, N. Cohen, N. Bril, M. Rein, G. Tsaban, H. Zelicha, A. Yaskolka Meir, L. Tene, B. Sarusy, P. Rosen, J.R. Hoffman, J.R. Stout, J. Thiery, U. Ceglarek, M. Stumvoll, M. Blüher, M.J. Stampfer, I. Shai, 2017. Intramyocellular triacylglycerol accumulation across weight loss strategies; Sub-study of the CENTRAL trial. PLoS One. 2017 Nov 30;12(11):e0188431. doi: 10.1371/journal.pone.0188431. eCollection 2017.

BACKGROUND: Intramyocellular triacylglycerol (IMTG) is utilized as metabolic fuel during exercise and is linked to insulin resistance, but the long-term effect of weight loss strategies on IMTG among participants with abdominal fat, remain unclear. METHODS: In an 18-month trial, sedentary participants with abdominal fat/dyslipidemia were randomized to either a low-fat (LF) or Mediterranean/low-carbohydrate (MED/LC) diet (including 28g·day-1 of walnuts). After 6-months, the participants were re-randomized to moderate intense physical activity (PA+) or non-physical activity (PA-). Magnetic resonance imaging (MRI) was used to quantify changes of IMTG, abdominal sub-depots, hepatic and intermuscular fats. RESULTS: Across the 277 participants [86% men, age = 48 years, body-mass-index (BMI) = 31kg/m2, visceral fat = 33%] 86% completed the 18-m trial. At baseline, women had higher IMTG than men (3.4% vs. 2.3%, p<0.001) and increased IMTG was associated with aging and higher BMI, visceral and intermuscular fats, HbA1c%, HDL-c and leptin (p<0.05), but not with intra-hepatic fat. After 18 month of intervention and a -3 kg mean weight loss, participants significantly increased IMTG by 25%, with a distinct effect in the MED/LCPA+ group as compared to the other intervention groups (57% vs. 9.5-18.5%, p<0.05). Changes in IMTG were associated with visceral and intermuscular fat, metabolic syndrome, insulin and leptin (p<0.05 for all), however, these associations did not remain after adjustment for visceral fat changes. CONCLUSIONS: Lifestyle strategies differentially affect IMTG accumulation; combination of exercise with decreased carbohydrate/increased unsaturated fat proportion intake greatly increase IMTG. Our findings suggest that increased IMTG during diet-induced moderate weight loss may not be directly related to cardiometabolic risk.

Almond consumption during energy restriction lowers truncal fat and blood pressure in compliant overweight or obese adults.

Dhillon, J., S-Y. Tan, R.D. Mattes, 2016. Almond consumption during energy restriction lowers truncal fat and blood pressure in compliant overweight or obese adults. J. Nutr. 146:2513–2509.

Background: The inclusion of almonds in an energy-restricted diet has been reported both to enhance or to have no effect on weight loss. Their effects specifically on visceral body fat stores during energy restriction have not been widely examined. In addition, almond consumption has been associated with reduced blood pressure (BP), but whether this is linked to or independent of changes in body composition has to our knowledge not been examined. Objective: We evaluated the effects of consuming almonds as part of an energy-restricted diet on body composition, specifically visceral adipose tissue (VAT) and BP, compared to a nut-free energy-restricted diet. Methods: A randomized controlled 12-wk clinical trial of 86 healthy adults [body mass index (in kg/m2): 25–40] was conducted. Participants were randomly assigned to 1 of 2 energy-restricted (500-kcal deficit/d) diets: an almond-enriched diet (AED) (15% energy from almonds) or a nut-free diet (NFD). A linear mixed-model analysis on primary outcomes such as body weight, body fat, VAT, and BP was performed on all participants [intention-to-treat (ITT) analysis] and compliant participants (complier analysis). Results: Body weight, truncal and total fat percentage, VAT, and systolic BP decreased after 12 wk of energy restriction in both the ITT and complier analyses (P< 0.05). The complier analysis (but not the ITT analysis) indicated a greater mean ± SEM reduction in truncal fat (AED: -1.21% ± 0.26%; NFD: -0.48% ± 0.24%; P = 0.025), total fat (AED: -1.79% ± 0.36%; NFD: -0.74% ± 0.33%; P = 0.035), and diastolic BP (AED: -2.71 ± 1.2 mm Hg; NFD: 0.815 ± 1.1 mm Hg; P = 0.029), and a greater tendency for VAT loss (AED: -8.19 ± 1.8cm2; NFD:-3.99 ± 1.7cm2; P=0.09) overtime in the AED group than the NFD group. Conclusions: Moderate almond consumption by compliant overweight and obese individuals during energy restriction results in greater proportional reductions of truncal and total body fat as well as diastolic BP and hence may help to reduce metabolic disease risk in obesity.

Intermuscular adipose tissue and thigh muscle area dynamics during an 18-month randomized weight loss trial.

Yaskolka, M.A., I. Shelef, D. Schwarzfuchs, Y. Gepner, L. Tene, H. Zelicha, G. Tsaban, A. Bilitzky, O. Komy, N. Cohen, N. Bril, M. Rein, D. Serfaty, S. Kenigsbuch, Y. Chassidim, L. Zeller, U. Ceglarek, M. Stumvoll, M. Blüher, J. Thiery, M.J. Stampfer, A. Rudich, I. Shai, 2016. Intermuscular adipose tissue and thigh muscle area dynamics during an 18-month randomized weight loss trial. J Appl Physiol. 121:518-527.

It remains unclear whether intermuscular adipose tissue (IMAT) has any metabolic influence or whether it is merely a marker of abnormalities, as well as what are the effects of specific lifestyle strategies for weight loss on the dynamics of both IMAT and thigh muscle area (TMA). We followed the trajectory of IMAT and TMA during 18-mo lifestyle intervention among 278 sedentary participants with abdominal obesity, using magnetic resonance imaging. We measured the resting metabolic rate (RMR) by an indirect calorimeter. Among 273 eligible participants (47.8 ± 9.3 yr of age), the mean IMAT was 9.6 ± 4.6 cm(2) Baseline IMAT levels were directly correlated with waist circumference, abdominal subdepots, C-reactive protein, and leptin and inversely correlated with baseline TMA and creatinine (P < 0.05 for all). After 18 mo (86.3% adherence), both IMAT (-1.6%) and TMA (-3.3%) significantly decreased (P < 0.01 vs. baseline). The changes in both IMAT and TMA were similar across the lifestyle intervention groups and directly corresponded with moderate weight loss (P < 0.001). IMAT change did not remain independently associated with decreased abdominal subdepots or improved cardiometabolic parameters after adjustments for age, sex, and 18-mo weight loss. In similar models, 18-mo TMA loss remained associated with decreased RMR, decreased activity, and with increased fasting glucose levels and IMAT (P < 0.05 for all). Unlike other fat depots, IMAT may not represent a unique or specific adipose tissue, instead largely reflecting body weight change per se. Moderate weight loss induced a significant decrease in thigh muscle area, suggesting the importance of resistance training to accompany weight loss programs.

Effects of diet composition on weight loss, metabolic factors and biomarkers in a 1-year weight loss intervention in obese women examined by baseline insulin resistance status.

Rock, C.L., S.W. Flatt, B. Pakiz, E.L.Quintana, D.D. Heath, B.K. Rana, L. Natarajan, 2016. Effects of diet composition on weight loss, metabolic factors and biomarkers in a 1-year weight loss intervention in obese women examined by baseline insulin resistance status. Metabolism. 65(11):1605-1613.

Background: Obesity is a risk factor for postmenopausal breast cancer incidence and pre- and postmenopausal breast cancer mortality, which may be explained by several metabolic and hormonal factors (sex hormones, insulin resistance, and inflammation) that are biologically related. Differential effects of dietary composition on weight loss and these metabolic factors may occur in insulin-sensitive vs. insulin-resistant obese women. Objective. To examine the effect of diet composition on weight loss and metabolic, hormonal and inflammatory factors in overweight/obese women stratified by insulin resistance status in a 1-year weight loss intervention. Methods and Results. Nondiabetic women who were overweight/obese (n = 245) were randomly assigned to a lower fat (20% energy), higher carbohydrate (65% energy) diet; a lower carbohydrate (45% energy), higher fat (35% energy) diet; or a walnut-rich (18% energy), higher fat (35% energy), lower carbohydrate (45% energy) diet. All groups lost weight at follow-up (P < 0.0001), with mean (SEM) percent loss of 9.2 (1.1)% in lower fat, 6.5 (0.9)% in lower carbohydrate, and 8.2 (1.0)% in walnut-rich groups at 12 months. The diet x time x insulin resistance status interaction was not statistically significant in the model for overall weight loss, although insulin sensitive women at 12 months lost more weight in the lower fat vs. lower carbohydrate group (7.5 kg vs 4.3 kg, P = 0.06), and in the walnut-rich vs. lower carbohydrate group (8.1 kg vs 4.3 kg, P = 0.04). Sex hormone binding globulin increased within each group except in the lower carbohydrate group at 12 months (P < 0.01). C-reactive protein and interleukin-6 decreased at follow-up in all groups (P < 0.01). Conclusions. Findings provide some support for differential effects of diet composition on weight loss depending on insulin resistance status. Prescribing walnuts is associated with weight loss comparable to a standard lower fat diet in a behavioral weight loss intervention. Weight loss itself may be the most critical factor for reducing the chronic inflammation associated with increased breast cancer risk and progression.

 

Consumption of walnuts in combination with other whole foods produces physiologic, metabolic, and gene expression changes in obese C57BL/6J high-fat–fed male mice.

Luo, T., O. Miranda-Garcia, A. Adamson, J. Hamilton-Reeve, D.K. Sullivan, J.M. Kinchen, N.F. Shay, 2016.  Consumption of walnuts in combination with other whole foods produces physiologic, metabolic, and gene expression changes in obese C57BL/6J high-fat–fed male mice. J Nutr. 146(9):1641-50.

Background: Although a reductionist approach has sought to understand the roles of individual nutrients and biochemicals in foods, it has become apparent that there can be differences when studying food components in isolation or within the natural matrix of a whole food. Objective: The objective of this study was to determine the ability of whole-food intake to modulate the development of obesity and other metabolic dysfunction in mice fed a high-fat, Western-style obesogenic diet. To test the hypothesis that an n–3 (ω-3) polyunsaturated fatty acid-rich food could synergize with other, largely polyphenol-rich foods by producing greater reductions in metabolic disease conditions, the intake of English walnuts was evaluated in combination with 9 other whole foods. Methods: Eight-week-old male C57Bl/6J mice were fed low-fat (LF; 10% fat) and high-fat (HF) control diets, along with an HF diet with 8.6% (wt:wt) added walnuts for 9 wk. The HF control diet contained 46% fat with added sucrose (10.9%, wt:wt) and cholesterol (1%, wt:wt); the added sucrose and cholesterol were not present in the LF diet. Other groups were provided the walnut diet with a second whole food—raspberries, apples, cranberries, tart cherries, broccoli sprouts, olive oil, soy protein, or green tea. All of the energy-containing whole foods were added at an energy level equivalent to 1.5 servings/d. Body weights, food intake, and glucose tolerance were determined. Postmortem, serum lipids and inflammatory markers, hepatic fat, gene expression, and the relative concentrations of 594 biochemicals were measured. Results: The addition of walnuts with either raspberries, apples, or green tea reduced glucose area under the curve compared with the HF diet alone (−93%, −64%, and −54%, respectively, P < 0.05). Compared with HF-fed mice, mice fed walnuts with either broccoli sprouts or green tea (−49% and −61%, respectively, P < 0.05) had reduced hepatic fat concentrations. There were differences in global gene expression patterns related to whole-food content, with many examples of differences in LF- and HF-fed mice, HF- and walnut-fed mice, and mice fed walnuts and walnuts plus other foods. The mean ± SEM increase in relative hepatic concentrations of the n–3 fatty acids α-linolenic acid, eicosapentanoic acid, and docosapentanoic acid in all walnut-fed groups was 124% ± 13%, 159% ± 11%, and 114% ± 10%, respectively (P < 0.0001), compared with LF- and HF-fed mice not consuming walnuts. Conclusions: In obese male mice, walnut consumption with a high-fat Western-style diet caused changes in hepatic fat concentrations, gene expression patterns, and fatty acid concentrations. The addition of a second whole food in combination with walnuts produced other changes in metabolite concentrations and gene expression patterns and other physiologic markers. Importantly, these substantial changes occurred in mice fed typical amounts of intake, representing only 1.5 servings each food/d.

Impact of providing walnut samples in a lifestyle intervention for weight loss: a secondary analysis of the HealthTrack trial.

Neale, E.P., L.C. Tapsell, A. Martin, M.J. Batterham, C. Wibisono, Y.C. Probst, 2016. Impact of providing walnut samples in a lifestyle intervention for weight loss: a secondary analysis of the HealthTrack trial. Food and Nutrition Research. 61:1, 1344522. doi:1080/16546628.2017.1344522.

Background: Being more specific about individual food choices may be advantageous for weight loss. Including a healthy food (e.g. walnuts) may help to expose effects. Objective: To examine the impact of including walnuts in diets for weight loss. Design: Secondary analysis of the HealthTrack lifestyle intervention trial. Overweight and obese participants were randomized to: usual care (C), interdisciplinary intervention including individualized dietary advice (I), or interdisciplinary intervention including 30 g walnuts/day (IW). Changes in body weight, energy intake, intake of key foods, physical activity, and mental health over three and 12 months were explored. Results: A total of 293 participants completed the intensive three-month study period, and 175 had data available at 12 months. The IW group achieved the greatest weight loss at three months. IW reported significant improvements in healthy food choices, and decreased intakes of discretionary foods/beverages, compared to C. Weight loss remained greatest in IW at 12 months. Discussion: Significant effects were seen after three months, with the IW group achieving greater weight loss and more favorable changes in food choices. Conclusions: Including 30 grams walnuts/day in an individualized diet produced weight loss and positive changes in food choice.

Walnuts consumed by healthy adults provide less available energy than predicted by the Atwater Factors.

Baer, D., S. Gebauer, J. Novotny, 2016. Walnuts consumed by healthy adults provide less available energy than predicted by the Atwater Factors. J Nutr. 146:1–5.

Background: Previous studies have shown that the metabolizable energy (ME) content (energy available to the body) of certain nuts is less than predicted by the Atwater factors. However, very few nuts have been investigated to date, and no information is available regarding the ME of walnuts. Objective: A study was conducted to determine the ME of walnuts when consumed as part of a typical American diet. Methods: Healthy adults (n = 18; mean age = 53.1 y; body mass index = 28.8 kg/m2) participated in a randomized crossover study with 2 treatment periods (3 wk each). The study was a fully controlled dietary feeding intervention in which the same base diet was consumed during each treatment period; the base diet was unsupplemented during one feeding period and supplemented with 42 g/d walnuts during the other feeding period. Base diet foods were reduced in equal proportions during the walnut period to achieve isocaloric food intake during the 2 periods. After a 9 d diet acclimation period, subjects collected all urine and feces for ;1 wk (as marked by a Brilliant Blue fecal collection marker) for analysis of energy content. Administered diets, walnuts, and fecal and urine samples were subjected to bomb calorimetry, and the resulting data were used to calculate the ME of the walnuts. Results: One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the value of 185 kcal/ serving (6.61 kcal/g) currently used for food labeling. The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001). Conclusion: Consistent with other tree nuts, Atwater factors overestimate the metabolizable energy value of walnuts. These results could help explain the observations that consumers of nuts do not gain excessive weight, and improve the accuracy for food labeling.

Effects of diet composition and insulin resistance status on plasma lipid levels in a weight loss intervention in women.

Le, T., S.W. Flatt, L. Natarajan, B. Pakiz, E.L. Quintana, D.D. Heath, B.K. Rana, C.L. Rock, 2016. Effects of diet composition and insulin resistance status on plasma lipid levels in a weight loss intervention in women. J Am Heart Assoc. 5(1). doi: 10.1161/JAHA.115.002771.

Background: Optimal macronutrient distribution of weight loss diets has not been established. The distribution of energy from carbohydrate and fat has been observed to promote differential plasma lipid responses in previous weight loss studies, and insulin resistance status may interact with diet composition and affect weight loss and lipid responses. Methods and Results: Overweight and obese women (n=245) were enrolled in a 1‐year behavioral weight loss intervention and randomly assigned to 1 of 3 study groups: a lower fat (20% energy), higher carbohydrate (65% energy) diet; a lower carbohydrate (45% energy), higher fat (35% energy) diet; or a walnut‐rich, higher fat (35% energy), lower carbohydrate (45% energy) diet. Blood samples and data available from 213 women at baseline and at 6 months were the focus of this analysis. Triglycerides, total cholesterol, and high‐ and low‐density lipoprotein cholesterol were quantified and compared between and within groups. Triglycerides decreased in all study arms at 6 months (P<0.05). The walnut‐rich diet increased high‐density lipoprotein cholesterol more than either the lower fat or lower carbohydrate diet (P<0.05). The walnut‐rich diet also reduced low‐density lipoprotein cholesterol in insulin‐sensitive women, whereas the lower fat diet reduced both total cholesterol and high‐density lipoprotein cholesterol in insulin‐sensitive women (P<0.05). Insulin sensitivity and C‐reactive protein levels also improved. Conclusions: Weight loss was similar across the diet groups, although insulin‐sensitive women lost more weight with a lower fat, higher carbohydrate diet versus a higher fat, lower carbohydrate diet. The walnut‐rich, higher fat diet resulted in the most favorable changes in lipid levels.

Key area: insulin resistance, lipids, walnuts/ weight management/weight, satiety,

Effects of hazelnut consumption on blood lipids and body weight: A systematic review and Bayesian meta-analysis.

S. Perna, A. Giacosa, G. Bonitta, C. Bologna, A. Isu, D. Guido, M. Rondanelli, 2016. Effects of hazelnut consumption on blood lipids and body weight: A systematic review and Bayesian meta-analysis. Nutrients. 8,747; doi:10.3390/nu8120747.

Hazelnuts are rich in monounsaturated fatty acids and antioxidant bioactive substances: their consumption has been associated with a decreased risk of cardiovascular disease events. A systematic review and a meta-analysis was performed to combine the results from several trials and to estimate the pooled (overall) effect of hazelnuts on blood lipids and body weight outcomes. Specifically, a Bayesian random effect meta-analysis of mean differences of ∆-changes from baseline across treatment (MD∆) (i.e., hazelnut-enriched diet vs. control diet) has been conducted. Nine studies representing 425 participants were included in the analysis. The intervention diet lasted 28–84 days with a dosage of hazelnuts ranging from 29 to 69 g/day. Out of nine studies, three randomized studies have been meta-analyzed showing a significant reduction in low-density lipoprotein (LDL) cholesterol (pooled MD∆ = −0.150 mmol/L; 95% highest posterior density interval (95% HPD) = −0.308; −0.003) in favor of a hazelnut-enriched diet. Total cholesterol showed a marked trend toward a decrease (pooled MD∆ = −0.127 mmol/L; 95% HPD = −0.284; 0.014) and high-density lipoprotein (HDL) cholesterol remained substantially stable (pooled MD∆ = 0.002 mmol/L; 95% HPD = −0.140; 0.147). No effects on triglycerides (pooled MD∆ = 0.045 mmol/L; 95% HPD = −0.195; 0.269) and body mass index (BMI) (pooled MD∆ = 0.062 kg/m2 ; 95% HPD = −0.293; 0.469) were found. Hazelnut-enriched diet is associated with a decrease of LDL and total cholesterol, while HDL cholesterol, triglycerides and BMI remain substantially unchanged.