Metabolic improvements associated with low-carbohydrate diet in overweight and obese adults: Contributions to public health nutrition

Abstract

Background: Overweight (OW) and obesity (OB) are major public health challenges associated with metabolic disorders, chronic diseases, and rising healthcare costs. Low-carbohydrate diets (LCDs) have emerged as cost-effective strategies for prevention and treatment. Objective: The objective of the study is to evaluate the effects of an LCD (≤130 g/day) on anthropometric, metabolic, hepatic, and renal parameters in OW and obese adults over 12 months. Methods: This open-label, non-randomized, self-controlled clinical trial included 34 adults with body mass index (BMI) ≥ 25 kg/m ² who received individualized nutritional counseling and followed an LCD for up to 12 months. Clinical and laboratory parameters were assessed at baseline and during follow-up (3–6 months and 7–12 months). Statistical analyses included generalized estimating equations and non-parametric tests with Bonferroni correction. Results: Participants achieved a mean weight loss of 10%, with reductions in BMI (−2.9 kg/m ²), waist circumference (−5.4 cm), and body fat percentage. Glycated hemoglobin decreased at 7–12 months (p <0.05), while insulin levels and insulin resistance declined at 3–6 months (p =0.0497 and p =0.037). Fasting glucose remained stable. Low-density lipoprotein cholesterol increased modestly at 7–12 months (p =0.035), whereas other lipid parameters showed no significant changes. Gamma-glutamyl transferase levels decreased (p =0.0341), with no adverse effects on renal or hepatic markers. Conclusion: An LCD was associated with improvements in glycemic control, body composition, insulin sensitivity, and liver enzymes without compromising renal function or lipid profiles, supporting its role in OB management and cardiometabolic risk reduction in primary care.

Keywords

Low-carbohydrate diet / Overweight / Obese / Metabolic health / Nutrition / Diet

Acknowledgments

The authors would like to thank the Coordination for the Improvement of Higher Education Personnel (CAPES) for their support in this study.

Funding

None.

Conflict of interest

The authors declare that they have no competing interests.

Author contributions

Conceptualization: Giselle Foureaux, Laryssa Rosa de Sousa Franckilin, Janaina Koenen, Daniela Godoy Neri Formal analysis: Janaina Koenen, Carlos Eduardo de Freitas Jorge, Daniela Godoy Neri, Giselle Foureaux Investigation: Giselle Foureaux, Laryssa Rosa de Sousa Franckilin, Janaina Koenen Methodology: Giselle Foureaux, Laryssa Rosa de Sousa Franckilin, Janaina Koenen, Maria Vitoria Cota de Abreu Writing – original draft: Giselle Foureaux, Laryssa Rosa de Sousa Franckilin, Ludmila Lizziane de Souza Lima, Flávio Eduardo Dias Araújo Freitas Writing – review & editing: Janaina Koenen, Carlos Eduardo de Freitas Jorge

Ethics approval and consent to participate

The study was approved by the local Research Ethics Committee and conducted in accordance with the Brazilian National Health Council’s guidelines under the CEP/CONEP system (approval number: 4.961.640; CAAE: 49593220.4.0000.5149). This study was registered at the Brazilian Registry of Clinical Trials (ReBEC) (registration no.: RBR-107jk4tn, UTN no.: U1111-1270-4313, registry link: https://ensaiosclinicos.gov.br/rg/RBR-107jk4tn) before participant enrollment. All participants provided written informed consent before undergoing any study-related procedures.

Consent for publication

All participants provided written informed consent for the publication of anonymized data and results.

Availability of data

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

References

[1] Garcia CAB, Meira KC, Souza AH, Oliveira ALG, Guimarães NS. Obesity and associated factors in Brazilian adults: Systematic review and meta-analysis of representative studies. Int J Environ Res Public Health. 2024; 21(8): 1022. doi: 10.3390/ijerph21081022

[2] National Obesity Forum; Public Health Collaboration. Eat Fat, Cut The Carbs and Avoid Snacking To Reverse Obesity and Type 2 Diabetes. London: National Obesity Forum, Public Health Collaboration ; 2016. Available from: https://phcuk.org/wp/content/uploads/2016/05/eat/fat/cut/the/carbs/and/avoid/snacking/to/reverse/obesity/and/type/2/diabetes/national/obesity/forum/public/health/collaboration.pdf [Last accessed on 2025 May 13]. https://phcuk.org/wp/content/uploads/2016/05/eat/fat/cut/the/carbs/and/avoid/snacking/to/reverse/obesity/and/type/2/diabetes/national/obesity/forum/public/health/collaboration.pdf

[3] World Health Organization. Obesity and Overweight. Geneva: World Health Organization; 2025. Available from: https://www.who.int/news/room/fact/sheets/detail/obesity-and-overweight [Last accessed on 2025 May 13]. https://www.who.int/news/room/fact/sheets/detail/obesity-and-overweight

[4] Centers for Disease Control and Prevention (CDC). Adult Obesity Facts (NHANES, 2021). Atlanta, GA: CDC; 2023. Available from: https://www.cdc.gov/obesity/adult/obesity-facts/index.html [Last accessed on 2025 Dec 08]. https://www.cdc.gov/obesity/adult/obesity-facts/index.html

[5] Tsao CW, Aday AW, Almarzooq ZI, et al. Heart disease and stroke statistics-2023 update: A report from the American heart association. Circulation. 2023; 147(8): e93-e621. doi: 10.1161/CIR.0000000000001123

[6] Brazilian Ministry of Health. Secretariat of Health Surveillance. Department of Health Analysis and Surveillance of Noncommunicable Diseases. Vigitel Brazil 2006-2021: Surveillance of Risk and Protective Factors for Chronic Diseases by Telephone Survey. Brasília, DF: Ministry of Health; 2022. Available from: https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/vigitel/vigitel/brasil/2006/2021/vigilancia/de/fatores/de/risco/e/protecao/para/doencas/cronicas/por/inquerito-telefonico.pdf [Last accessed on 2025 Apr 24]. https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/vigitel/vigitel/brasil/2006/2021/vigilancia/de/fatores/de/risco/e/protecao/para/doencas/cronicas/por/inquerito-telefonico.pdf

[7] Pan American Health Organization (PAHO). Country Profile of Capacity and Response to Noncommunicable Diseases and Their Risk Factors in the Region of the Americas. Country Capacity Survey Results of 2015; 2018. Washington, DC. Available from: https://www.paho.org/sites/default/files/9789275119273_eng.pdf [Last accessed on 2025 Apr 24]. https://www.paho.org/sites/default/files/9789275119273_eng.pdf

[8] Brazilian Ministry of Health. National Food and Nutrition Policy. 2nd ed. Brasília, DF: Ministry of Health; 2017. (Series B. Basic Health Texts). [Em Português] Available from: https://bvsms.saude.gov.br/bvs/publicacoes/politica_nacional_alimentacao_nutricao.pdf [Last accessed on 2025 May 13]. https://bvsms.saude.gov.br/bvs/publicacoes/politica_nacional_alimentacao_nutricao.pdf

[9] Brazilian Ministry of Health. National Food and Nutrition Policy. Brasília, DF: Ministry of Health. [Em Português]; 2020. Available from: https://www.gov.br/saude/pt/br/composicao/saps/pnan [Last accessed on 2025 May 13]. https://www.gov.br/saude/pt/br/composicao/saps/pnan

[10] World Health Organization. Obesity and Overweight. Geneva: World Health Organization; 2020. Available from: https://www.paho.org/en [Last accessed on 2025 May 04]. https://www.paho.org/en

[11] Zylke JW, Bauchner H. The unrelenting challenge of obesity. JAMA. 2016; 315(21): 2277-2278. doi: 10.1001/jama.2016.6190

[12] Mariath AB, Grillo LP, Silva RO, et al. Obesity and risk factors for the development of chronic non-transmissible diseases among consumers in a foodservice unit. Cad Saude Publica. 2007; 23(4): 897-905. doi: 10.1590/s0102-311x2007000400017

[13] Cordeiro R, Salles MB, Azevedo MB. Benefits and risks of the low-carbohydrate diet. Health Focus J. 2017; 9: 714-722.

[14] World Health Organization (WHO). Physical Status: The Use and Interpretation of Anthropometry. Geneva: World Health Organization; 1995. Available from: https://www.who.int/publications/i/item/9241208546 [Last accessed on 2025 May 04]. https://www.who.int/publications/i/item/9241208546

[15] De Onis M, Onyango AW, Borghi E, Siyam A, Nishida C, Siekmann J. Development of a WHO growth reference for school-aged children and adolescents. Bull World Health Organ. 2007; 85(9): 660-667. doi: 10.2471/blt.07.043497

[16] Tavares EL, Anjos LA. Perfil antropométrico da população idosa brasileira. Resultados da Pesquisa Nacional sobre Saúde e Nutrição. Cad Saude Publica. 1999; 15(4): 759-768. doi: 10.1590/S0102-311X1999000400010

[17] Institute of Medicine (US). Weight Gain during Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press; 2009. doi: 10.17226/12584

[18] Brazilian Ministry of Health. Health in Brazil 2020-2021; 2021. An Analysis of the Health Situation. Brasília, DF: Ministry of Health. [Em Português] Available from: https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/vigilancia/saude_brasil_2020_2021_situacao_saude_web.pdf/view [Last accessed on 2025 Mar 08]. https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/vigilancia/saude_brasil_2020_2021_situacao_saude_web.pdf/view

[19] DeFronzo RA, Abdul-Ghani MA. Treatment of prediabetes. World J Diabetes. 2015; 6(12): 1207-1222. doi: 10.4239/wjd.v6.i12.1207

[20] Leite L, Rocha ED, Brandão-Neto J. Obesity: An inflammatory disease. J Health Sci. 2009; 2(2): 85-95. doi: 10.15448/1983-652X.2009.2.6238

[21] Brazilian Ministry of Health. Secretariat of Health Surveillance. Department of Health Analysis and Surveillance of Noncommunicable Diseases. Strategic Action Plan for Coping with Chronic Noncommunicable Diseases and Conditions in Brazil 2021-2030. Brasília, DF: Ministry of Health; 2021b. Available from: https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/doencas/cronicas/nao-transmissiveis-dcnt/09-plano-de-dant-2022_2030.pdf [Last accessed on 2025 May 19]. https://www.gov.br/saude/pt/br/centrais/de/conteudo/publicacoes/svsa/doencas/cronicas/nao-transmissiveis-dcnt/09-plano-de-dant-2022_2030.pdf

[22] Wood IS, De Heredia FP, Wang B, Trayhurn P. Cellular hypoxia and adipose tissue dysfunction in obesity. Proc Nutr Soc. 2009; 68(4): 370-377. doi: 10.1017/S0029665109990206

[23] Neels JG, Olefsky JM. Inflamed fat: What starts the fire? J Clin Invest. 2006; 116(1): 33-35. doi: 10.1172/JCI27280

[24] Prado WL, Lima LC, Caranti DA, et al. Obesity and inflammatory adipokines: practical implications for exercise prescription. Brazilian J Sports Med. 2009; 15(5): 378-383. doi: 10.1590/S1517-86922009000600012

[25] Saad MJA. Obesity, diabetes, and endothelium: Molecular interactions. In: Endothelium and Cardiovascular Diseases. Cham: Springer; 2018. p. 639-652. doi: 10.1016/B978-0-12-812348-5.00044-1

[26] Sippel CA, Bastian RMA, Giovanella J, Faccin C, Contini V, Dal Bosco SMD. Inflammatory processes of obesity. J Health Care. 2014; 12(42): 48-56. doi: 10.13037/rbcs.vol12n42.2310

[27] Hildebrandt A, Ibrahim M, Peltzer N. Cell death and inflammation during obesity: “Know my methods, WAT(son)”. Cell Death Differ. 2022; 30(2): 279-292. doi: 10.1038/s41418-022-01062-4

[28] Papadopoulou SK, Nikolaidis PT. Low-carbohydrate diet and human health. Nutrients. 2023; 15(8): 2004. doi: 10.3390/nu15082004

[29] Hu T, Yao L, Reynolds K, et al. The effects of a low carbohydrate diet on appetite: A randomized controlled trial. Nutr Metab Cardiovasc Dis. 2016; 26(6): 476-488. doi: 10.1016/j.numecd.2015.11.011

[30] Harvey W. On Corpulence in Relation to Disease: With Some Remarks on Diet. London: Henry Renshaw; 1872.

[31] Cutting W. The treatment of obesity. J Clin Endocrinol Metab. 1943; 3(2): 85-88. doi: 10.1210/jcem-3-2-85

[32] Betoni F, Zanardo VPS, Ceni GC. Evaluation of the use of fad diets by patients attending a specialized nutrition outpatient clinic and their implications for metabolism. Health Sci Commun. 2010; 9(3): 430-440. doi: 10.5585/conssaude.v9i3.2322

[33] Sampaio LPB. Ketogenic diet for epilepsy treatment. Arq Neuropsiquiatr. 2016; 74(10): 842-848. doi: 10.1590/0004-282X20160116

[34] Goldenberg JZ, Day A, Brinkworth GD, et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: Systematic review and meta-analysis of published and unpublished randomized trial data. BMJ. 2021; 372:m4743. doi: 10.1136/bmj.m4743

[35] Skytte MJ, Samkani A, Petersen AD, et al. A carbohydrate-reduced high-protein diet improves HbA1c and liver fat content in weight-stable participants with type 2 diabetes: A randomised controlled trial. Diabetologia. 2019; 62(11): 2066-2078. doi: 10.1007/s00125-019-4956-4

[36] Wang LL, Wang Q, Hong Y, et al. The effect of low-carbohydrate diet on glycemic control in patients with type 2 diabetes mellitus. Nutrients. 2018; 10(6): 661. doi: 10.3390/nu10060661

[37] Volek JS, Yancy WS Jr. , Gower BA, et al. Expert consensus on nutrition and lower carbohydrate diets: An evidence- and equity-based approach to dietary guidance. Front Nutr. 2024; 11: 1376098. doi: 10.3389/fnut.2024.1376098

[38] Trumbo P, Schlicker S, Yates AA, Poos M, Food and Nutrition Board of the Institute of Medicine, The National Academies. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. J Am Diet Assoc. 2002; 102(11): 1621-1630. doi: 10.1016/S0002-8223(02)90346-9

[39] Kuo JC. Ketogenic diet and epigenetic modulation: Role in weight loss and metabolic disease. Nutrients. 2019; 11(9): 2163. doi: 10.3390/nu11092163

[40] Noakes TD, Windt J. Evidence that supports the prescription of low-carbohydrate high-fat diets: A narrative review. Br J Sports Med. 2017; 51(2): 133-139. doi: 10.1136/bjsports-2016-096491

[41] Perna S, Spadaccini D, Rondanelli M, et al. Effectiveness of a hypocaloric and low-carbohydrate diet on visceral adipose tissue and glycemic control in overweight and obese patients with type 2 diabetes. Bahrain Med Bull. 2019; 41(3): 159-166.

[42] Petrisko M, Brownlow B, DeLuca M, et al. Biochemical, anthropometric, and physiological responses to carbohydrate-restricted diets versus a low-fat diet in obese adults: A randomized crossover trial. J Med Food. 2020; 23(3): 206-211. doi: 10.1089/jmf.2019.0059

[43] Koppel S, Swerdlow RH. Neuroketotherapeutics: A modern review of a century-old therapy. Neurochem Int. 2018; 117: 114-125. doi: 10.1016/j.neuint.2017.10.003

[44] Manninen AH. Metabolic effects of the very-low-carbohydrate diets: Misunderstood “villains” of human metabolism. J Int Soc Sports Nutr. 2004; 1(2): 7-11. doi: 10.1186/1550-2783-1-2-7

[45] Phinney SD. Ketogenic diets and physical performance. Nutr Metab (Lond). 2004; 1: 2. doi: 10.1186/1743-7075-1-2

[46] Ranjan A, Schmidt S, Madsbad S, et al. Low-carbohydrate diet impairs the effect of glucagon in the treatment of insulin-induced mild hypoglycemia: A randomized crossover study. Diabetes Care. 2017; 40(1): 132-135. doi: 10.2337/dc16-1694

[47] Kjellberg J, Tange Larsen A, Ibsen R, Højgaard B. The socioeconomic burden of obesity. Obes Facts. 2017; 10(5): 493-502. doi: 10.1159/000480404

[48] Nilson EAF, Andrade RDC, Brito DA, Oliveira ML. Costs attributable to obesity, hypertension, and diabetes in the Unified Health System, Brazil, 2018 costos atribuibles a la obesidad, la hipertensión y la diabetes en el sistema único de salud de Brasil, 2018. Rev Panam Salud Publica. 2020; 44: e32. doi: 10.26633/RPSP.2020.32

[49] Kossoff EH, Zupec-Kania BA, Amark PE, et al. Optimal clinical management of children receiving dietary therapies for epilepsy: Updated recommendations of the international ketogenic diet study group. Epilepsia Open. 2018; 3(2): 175-192. doi: 10.1002/epi4.12225

[50] Chawla S, Silva FT, Medeiros SA, Mekary RA, Radenkovic D. The effect of low-fat and low-carbohydrate diets on weight loss and lipid levels: A systematic review and meta-analysis. Nutrients. 2020; 12(12): 3774. doi: 10.3390/nu12123774

[51] Sackner-Bernstein J, Kanter D, Kaul S. Dietary intervention for overweight and obese adults: Comparison of low-carbohydrate and low-fat diets. A meta-analysis. PLoS One. 2015; 10(10): e0139817. doi: 10.1371/journal.pone.0139817

[52] Pogozelski W, Arpaia N, Priore S. The metabolic effects of low-carbohydrate diets and incorporation into a biochemistry course. Biochem Mol Biol Educ. 2005; 33(2): 91-100. doi: 10.1002/bmb.2005.49403302091

[53] Stentz FB, Brewer A, Wan J, et al. Remission of pre-diabetes to normal glucose tolerance in obese adults with high-protein versus high-carbohydrate diet: Randomized control trial. BMJ Open Diabetes Res Care. 2016; 4(1): e000258. doi: 10.1136/bmjdrc-2016-000258

[54] Peiró C, Romacho T, Azcutia V, et al. Inflammation, glucose, and vascular cell damage: The role of the pentose phosphate pathway. Cardiovasc Diabetol. 2016; 15(1): 82. doi: 10.1186/s12933-016-0406-2

[55] Moore LL, Visioni AJ, Qureshi MM, Bradlee ML, Ellison RC, D’Agostino R. Weight loss in overweight adults and the long-term risk of hypertension. Arch Intern Med. 2005; 165(11): 1298-1303. doi: 10.1001/archinte.165.11.1298

[56] Pfeiffer AFH, Kraus A, Albrecht S, et al. The effects of different quantities and qualities of protein intake in people with diabetes mellitus. Nutrients. 2020; 12(2): 365. doi: 10.3390/nu12020365

[57] Gregg E, Jakicic J, Blackburn G, et al. Association of the magnitude of weight loss and changes in physical fitness with long-term cardiovascular disease outcomes in overweight or obese people with type 2 diabetes: A post-hoc analysis of the look AHEAD randomised clinical trial. Lancet Diabetes Endocrinol. 2016; 4(11): 913-921. doi: 10.1016/S2213-8587(16)30162-0

[58] Hamman RF, Wing RR, Edelstein SL, et al. Effect of weight loss with lifestyle intervention on risk of diabetes. Diabetes Care. 2006; 29(9): 2102-2107. doi: 10.2337/dc06-0560

[59] Ross R, Neeland IJ, Yamashita S, et al. Waist circumference as a vital sign in clinical practice: A consensus statement from the IAS and ICCR working group on visceral obesity. Nat Rev Endocrinol. 2020; 16(3): 177-189. doi: 10.1038/s41574-019-0310-7

[60] Dehghan M, Mente A, Zhang X, et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): A prospective cohort study. Lancet. 2017; 390(10107): 2050-2062. doi: 10.1016/S0140-6736(17)32252-3

[61] Ivanova E, Myasoedova VA, Melnichenko AA, Grechko AV, Orekhov AN. Small dense low-density lipoprotein as biomarker for atherosclerotic diseases. Oxid Med Cell Longev. 2017; 2017: 1273042. doi: 10.1155/2017/1273042

[62] Feoli AMP, Muniz LC, Dorneles GP, Duarte MM, Andrade VM. Melhora do estilo de vida reduz o Índice de Castelli 1 em indivíduos com síndrome metabólica. Saúde Pesqui. 2018; 11(3): 467-472. doi: 10.17765/1983-1870.2018v11n3p467-474

[63] Da Luz PL, Favarato D, Faria-Neto JR Jr. , Lemos P, Chagas AC. High ratio of triglycerides to HDL-cholesterol predicts extensive coronary disease. Clinics (Sao Paulo). 2008; 63(4): 427-432. doi: 10.1590/S1807-59322008000400003

[64] Bazzano LA, Hu T, Reynolds K, et al. Effects of low-carbohydrate and low-fat diets: A randomized trial. Ann Intern Med. 2014; 161(5): 309-318. doi: 10.7326/M14-0180

[65] Wiesner P, Watson KE. Triglycerides: A reappraisal. Trends Cardiovasc Med. 2017; 27(6): 428-432. doi: 10.1016/j.tcm.2017.01.001

[66] Banks WA, Farr SA, Salameh TS, et al. Triglycerides cross the blood-brain barrier and induce central leptin and insulin receptor resistance. Int J Obes (Lond). 2018; 42(3): 391-397. doi: 10.1038/ijo.2017.274

[67] Devries MC, Sithamparapillai A, Brimble KS, et al. Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: A systematic review and meta-analysis. J Nutr. 2018; 148(11): 1760-1775. doi: 10.1093/jn/nxy196

[68] Tirosh A, Golan R, Harman-Boehm I, et al. Renal function following three distinct weight loss dietary strategies during 2 years of a randomized controlled trial. Diabetes Care. 2013; 36(8): 2225-2232. doi: 10.2337/dc12-1846

[69] Ahn HR, Shin MH, Nam HS, et al. The association between liver enzymes and risk of type 2 diabetes: The namwon study. Diabetol Metab Syndr. 2014; 6: 14. doi: 10.1186/1758-5996-6-14

[70] Gautier A, Balkau B, Lange C, et al. Risk factors for incident type 2 diabetes in individuals with a BMI of <27 kg/m²: The role of gamma-glutamyltransferase. Data from the epidemiological study on the insulin resistance syndrome (DESIR). Diabetologia. 2010; 53(2): 247-253. doi: 10.1007/s00125-009-1579-2

[71] Zeng XF, Varady KA, Wang XD, et al. The role of dietary modification in the prevention and management of metabolic dysfunction-associated fatty liver disease: An international multidisciplinary expert consensus. Metabolism. 2024; 161: 156028. doi: 10.1016/j.metabol.2024.156028

[72] Zinn C, North S, Donovan K, Muir C, Henderson G. Low-carbohydrate, healthy-fat eating: A cost comparison with national dietary guidelines. Nutr Diet. 2020; 77(3): 283-291. doi: 10.1111/1747-0080.12566

[73] Sato J, Kanazawa A, Makita S, et al. A randomized controlled trial of 130 g/day low-carbohydrate diet in type 2 diabetes with poor glycemic control. Clin Nutr. 2017; 36(4): 992-1000. doi: 10.1016/j.clnu.2016.06.014