Low-Carbohydrate vs. Low-Fat Diets for Weight Loss and Health

Currently, obesity treatment rests on the "calories-in, calories-out" (CICO) rule, formally named the energy balance theory (EBT). It maintains that body weight (BW) increases as food calories are greater than expended calories but decreases when the opposite occurs; hence, weight stability is expected at energy balance meaning that over time energy-in equals energy-out. It follows that dietary regimens with identical energy content should evoke similar amounts of weight and fat loss with only minor differences that follow from diet's macronutrient composition, e.g., diet-induced glycogen depletion and water excretion. A vast collection of evidence shows, however, that low-carbohydrate diets typically result in much greater weight and fat loss than isocaloric low-fat diets. Furthermore, our recent mathematical analysis demonstrated that weight stability coincides with a persistent energy imbalance and not otherwise. As an alternative, the mass balance model (MBM) was proposed that fitted weight loss data and explained the often superior weight loss evoked by low-carbohydrate diets versus low-fat diets. Here, we expand on these observations by computationally contrasting the predictions of both models in two scenarios described in the literature: altering the diet's macronutrient composition while energy intake is kept at weight maintenance level; and the weight loss response as diet composition is changed under untreated type 1 diabetes. Our results indicate that MBM predictions are remarkably accurate while those of the EBT are clearly erroneous. These findings may represent the beginning of a paradigm shift in obesity research.

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An assessment of low carbohydrate or low fat diets for weight loss at two year’s follow-up

Diabetic Medicine ◽

10.1111/j.1464-5491.2009.02926.x ◽

2009 ◽

Cited By ~ 1

Author(s):

PA Dyson ◽

S Beatty ◽

DR Matthews

Keyword(s):

Weight Loss ◽

Low Fat ◽

Low Carbohydrate ◽

Fat Diets

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Abstract MP63: Randomized Trials of Low-Fat vs. Other Diet Interventions on Weight Loss: A Meta-Analysis

Circulation ◽

10.1161/circ.129.suppl_1.mp63 ◽

2014 ◽

Vol 129 (suppl_1) ◽

Author(s):

Deirdre K Tobias ◽

Mu Chen ◽

Walter Willett ◽

Frank B Hu

Keyword(s):

Weight Loss ◽

Randomized Trials ◽

Dietary Intervention ◽

Meta Analysis ◽

Dietary Interventions ◽

Low Fat ◽

Intervention Intensity ◽

Low Carbohydrate ◽

Fat Diets

Introduction: The effectiveness of low-fat diets for weight loss has been debated for decades. Dozens of randomized control trials (RCTs) have assessed whether decreasing the intake of total fat leads to weight loss, giving mixed results. Hypothesis: We hypothesized that low-fat dietary interventions do not lead to greater weight loss when comparator diet intervention intensity is considered. Methods: We conducted a systematic review and meta-analysis. RCTs were included if they compared a low-fat dietary intervention to any control diet with at least 1 year of follow-up. We estimated the combined fixed effect inverse variance weighted mean difference of low-fat vs. comparison diets. Several a priori stratified analyses were considered to explore heterogeneity. Results: Fifty studies met inclusion criteria, reporting 1-10 years of follow-up on 70,054 participants. Overall, low-fat dietary interventions resulted in 0.51kg greater weight loss compared to other diets (95% CI = -0.62, -0.40, p<0.001; I2 = 83%). However, when trials where greater attention was given to the low-fat group were excluded, comparator diets led to greater weight loss than low-fat diets (n=30; WMD=0.87, 95% CI=0.56, 1.17, p<0.001). Similarly, when the type of comparator diet was considered, low-fat diets were only beneficial compared to control groups who were simply asked to maintain their usual diet (n=18; WMD = -1.03, 95% CI = -1.18, -0.88, p<0.001). When equal attention was given to intervention groups, low-carbohydrate diets (n=15; WMD = 1.13kg, 95% CI = 0.53, 1.73, p<0.001) and other “healthy” diets without a low-fat component (n=20; WMD = 0.77kg, 95% CI = 0.42, 1.13, p<0.001) led to greater weight loss than low-fat diets. Comparison diets, irrespective of type, were associated with 1.30kg greater weight loss than low-fat diets when the interventions were intended to be isocaloric (n=19; 95% CI = 0.92, 1.69, p<0.001). Conclusions: Low-fat dietary interventions are not more effective than other diets for weight loss when differences in intervention intensity between treatment groups are considered. Rather, evidence from long-term (>=1 year) randomized trials indicates low-carbohydrate or other healthful dietary pattern interventions without a low-fat focus may be more effective for weight loss than low-fat dietary interventions. Further evidence is needed to establish the role of these interventions in longer-term weight loss and weight maintenance.

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Examining differences between overweight women and men in 12-month weight loss study comparing healthy low-carbohydrate vs. low-fat diets

International Journal of Obesity ◽

10.1038/s41366-020-00708-y ◽

2020 ◽

Vol 45 (1) ◽

pp. 225-234

Author(s):

Lucia Aronica ◽

Joseph Rigdon ◽

Lisa C. Offringa ◽

Marcia L. Stefanick ◽

Christopher D. Gardner

Keyword(s):

Weight Loss ◽

Fat Mass ◽

Lean Mass ◽

Secondary Analysis ◽

Low Fat ◽

Primary Analysis ◽

Biological Sex ◽

Low Carbohydrate ◽

Fat Diets ◽

And Behavior

Abstract Background/objectives Biological sex factors and sociocultural gender norms affect the physiology and behavior of weight loss. However, most diet intervention studies do not report outcomes by sex, thereby impeding reproducibility. The objectives of this study were to compare 12-month changes in body weight and composition in groups defined by diet and sex, and adherence to a healthy low carbohydrate (HLC) vs. healthy low fat (HLF) diet. Participants/methods This was a secondary analysis of the DIETFITS trial, in which 609 overweight/obese nondiabetic participants (age, 18–50 years) were randomized to a 12-month HLC (n = 304) or HLF (n = 305) diet. Our first aim concerned comparisons in 12-month changes in weight, fat mass, and lean mass by group with appropriate adjustment for potential confounders. The second aim was to assess whether or not adherence differed by diet-sex group (HLC women n = 179, HLC men n = 125, HLF women n = 167, HLF men n = 138). Results 12-month changes in weight (p < 0.001) were different by group. HLC produced significantly greater weight loss, as well as greater loss of both fat mass and lean mass, than HLF among men [−2.98 kg (−4.47, −1.50); P < 0.001], but not among women. Men were more adherent to HLC than women (p = 0.02). Weight loss estimates within group remained similar after adjusting for adherence, suggesting adherence was not a mediator. Conclusions By reporting outcomes by sex significant weight loss differences were identified between HLC and HLF, which were not recognized in the original primary analysis. These findings highlight the need to consider sex in the design, analysis, and reporting of diet trials.

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An assessment of low-carbohydrate or low-fat diets for weight loss at 2 year’s follow-up

Diabetic Medicine ◽

10.1111/j.1464-5491.2010.02926.x ◽

2010 ◽

Vol 27 (3) ◽

pp. 363-364 ◽

Cited By ~ 8

Author(s):

P. A. Dyson ◽

S. Beatty ◽

D. R. Matthews

Keyword(s):

Weight Loss ◽

Low Fat ◽

Low Carbohydrate ◽

Fat Diets

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Effects of Low-Carbohydrate vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors

Archives of Internal Medicine ◽

10.1001/archinte.166.3.285 ◽

2006 ◽

Vol 166 (3) ◽

pp. 285 ◽

Cited By ~ 605

Author(s):

Alain J. Nordmann ◽

Abigail Nordmann ◽

Matthias Briel ◽

Ulrich Keller ◽

William S. Yancy ◽

...

Keyword(s):

Risk Factors ◽

Weight Loss ◽

Cardiovascular Risk ◽

Cardiovascular Risk Factors ◽

Low Fat ◽

Low Carbohydrate ◽

Fat Diets

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Adherence to low‐carbohydrate and low‐fat diets in relation to weight loss and cardiovascular risk factors

Obesity Science & Practice ◽

10.1002/osp4.23 ◽

2016 ◽

Vol 2 (1) ◽

pp. 24-31 ◽

Cited By ~ 9

Author(s):

T. Hu ◽

L. Yao ◽

K. Reynolds ◽

T. Niu ◽

S. Li ◽

...

Keyword(s):

Risk Factors ◽

Weight Loss ◽

Cardiovascular Risk ◽

Cardiovascular Risk Factors ◽

Low Fat ◽

Low Carbohydrate ◽

Fat Diets

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Abstract MP060: Effect of Low Carbohydrate Diets versus Low Fat Diets on Cardiovascular Risk Factors: A Meta-Analysis of Randomized Controlled Trials

Circulation ◽

10.1161/circ.125.suppl_10.amp060 ◽

2012 ◽

Vol 125 (suppl_10) ◽

Author(s):

Tian Hu ◽

Katherine Mills ◽

Lu Yao ◽

Kathryn Demanelis ◽

Mohamed Eloustaz ◽

...

Keyword(s):

Risk Factors ◽

Body Mass Index ◽

Weight Loss ◽

Randomized Controlled Trials ◽

Hdl Cholesterol ◽

Controlled Trials ◽

Low Fat ◽

Randomized Controlled ◽

Low Carbohydrate ◽

Fat Diets

Obesity is a major public health problem in the US population. Low carbohydrate diets are popular as a means of weight loss; however, there is concern for adverse effects on cardiovascular (CV) risk factors. We conducted a meta-analysis of randomized controlled trials comparing the effect of low carbohydrate diets (≤45% of energy from carbohydrates) versus low fat diets (≤30% of energy from fat) on CV risk factors, including systolic and diastolic blood pressure, total cholesterol, high-density-lipoprotein (HDL) cholesterol, low-density-lipoprotein (LDL) cholesterol, triglycerides, body mass index, waist circumference, fasting blood glucose and serum insulin. We searched MEDLINE, EMBASE, Web of Science and the Cochrane Database of Systematic Reviews, and manually examined references in selected articles and relevant literature reviews. Information on participant characteristics, trial design and duration, dietary composition, and CV risk factors were extracted using a standardized protocol. Random effects models were used to pool mean differences between CV risk factors on the two diets. From 785 potentially relevant publications, 23 randomized controlled trials compared low carbohydrate diets with low fat diets with intervention duration ≥ 6 months and reported CV risk factors as primary outcomes. These studies included data from 2,961 participants in total. The average percent of energy from carbohydrate intake was 20.7% on low carbohydrate diets and the average percent of energy from fats was 25.9% on low fat diets. Compared to participants on low fat diets, those on low carbohydrate diets showed favorable changes in HDL cholesterol, triglycerides and body mass index, with pooled net changes (95% CI) of 3.2 mg/dL (1.9, 4.5), -13.0 mg/dL (-17.3, -7.8) and -0.4 kg/m2 (-0.7, -0.1), respectively. After removing studies without intention-to-treat analysis, the change in body mass index was no longer significant (N=16). Changes in total and LDL cholesterol favored low fat diets, but after accounting for publication bias, results were no longer significant for total, LDL and HDL cholesterol. In conclusion, our findings show that low carbohydrate diets were at least as effective as low fat diets for weight loss, and did not have significant adverse effects on other CV risk factors. In fact, low carbohydrate diets had a significant and favorable impact on triglycerides. These findings suggest that low carbohydrate diets can be recommended to obese persons with CV risk factors for the purpose of weight loss.

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The Effect of Low-Fat and Low-Carbohydrate Diets on Weight Loss and Lipid Levels: A Systematic Review and Meta-Analysis

Nutrients ◽

10.3390/nu12123774 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3774

Author(s):

Shreya Chawla ◽

Fernanda Tessarolo Silva ◽

Sofia Amaral Medeiros ◽

Rania A. Mekary ◽

Dina Radenkovic

Keyword(s):

Weight Loss ◽

Total Cholesterol ◽

Meta Analysis ◽

Density Lipoprotein ◽

Lipoprotein Cholesterol ◽

Average Weight ◽

Low Fat ◽

Low Carbohydrate Diet ◽

Low Carbohydrate ◽

Fat Diets

Background: The rise in obesity has emphasised a focus on lifestyle and dietary habits. We aimed to address the debate between low-carbohydrate and low-fat diets and compare their effects on body weight, low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), total cholesterol, and triglycerides in an adult population. Method: Medline and Web of Science were searched for randomised controlled trials (RCTs) comparing low-fat and low-carbohydrate diets up to September 2019. Three independent reviewers extracted data. Risk of bias was assessed using the Cochrane tool. The meta-analysis was stratified by follow-up time using the random-effects models. Results: This meta-analysis of 38 studies assessed a total of 6499 adults. At 6–12 months, pooled analyses of mean differences of low-carbohydrate vs. low-fat diets favoured the low-carbohydrate diet for average weight change (mean difference −1.30 kg; 95% CI −2.02 to −0.57), HDL (0.05 mmol/L; 95% CI 0.03 to 0.08), and triglycerides (TG) (−0.10 mmol/L; −0.16 to −0.04), and favoured the low-fat diet for LDL (0.07 mmol/L; 95% CI 0.02 to 0.12) and total cholesterol (0.10 mmol/L; 95% CI 0.02 to 0.18). Conclusion and Relevance: This meta-analysis suggests that low-carbohydrate diets are effective at improving weight loss, HDL and TG lipid profiles. However, this must be balanced with potential consequences of raised LDL and total cholesterol in the long-term.

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