Hannah Perez,

Zama Middle High School - Department of Defense

Abstract

Obesity is a universal health issue, and finding effective dietary interventions is crucial. This paper examines the vegan diet and high protein, animal-based diet in the management and prevention of obesity.

Both diet patterns can lead to weight loss by different means, but the high fiber approach has more benefits with, likely, fewer risks to health, and only if of course well-planned. Additionally, levels of long-term adherence will come into play in both diet patterns, and therefore motivations to change dietary behaviors to find an approach that can be maintained for a prolonged period while providing a nutritionally adequate diet are of genuine importance.

Introduction

Obesity is a global phenomenon, and black hole that is a major factor in chronic disease, specifically Type 2 diabetes and cardiovascular disease. Sustainable dietary approaches are an important component to both managing obesity and preventing and reducing the ingrained increase in obesity prevalence. This paper is a brief, evidence informed critical comparison of vegan diets, and high protein, animal-based diet patterns, including the carnivore diet, in their features and individual mechanics, and evidence to support the management and or prevention of obesity.

Discussion

Diets and Obesity Outcomes

This review of literature incorporates systematic reviews, meta-analyses, and randomized controlled trials (RCTs) of vegan diets compared to high-protein (including carnivore), animal-based diets on managing and preventing obesity. This review examines how these diets impact not only body weight, body composition, and cardiometabolic markers, but also how they impact the gut microbiome, while also considering the relevant concerns of nutritional adequacy and long-term sustainability/utilization for the obese individual.

Dietary Definitions

Vegan Diet: Foods consisting of plant-derived foods only (vegetables, grains, nuts and fruits) with no animal products (meat, poultry, fish, dairy and dairy products, eggs, honey). It is considered to be high carbohydrate and fiber, moderately high protein, and low total fat. In comparison, a high-protein, animal-based diet may have a macronutrient distribution that resembles 20-40% protein, 60-80% fat, and <5% carbohydrates. Data were extracted from scientific articles (n=100) with primary literature being meta-analyses and systematic reviews of RCT's, and/or observational studies. The primary outcome measures were body weight, BMI, fat mass, and lean mass measures; along with cardiometabolic markers (HbA1c, cholesterol, blood pressure, etc.).

High-Protein, Animal-based Diet: Mostly refers to being mostly animal based, with a focus on protein consumption. May have macronutrient distributions that resemble 20-40% protein, 60-80% fat, and <5% carbohydrates causing a positive association of animal protein consumption with obesity risk

Data Collection and Analysis: Data from scientific articles, including both meta-analyses and systematic reviews of RCTs and observational studies, were collected. The main outcome measures were change in body weight, BMI, fat mass, and lean mass, as well as a number of cardiometabolic markers (HbA1c, cholesterol, blood pressure, etc.). The synthesis was to inform evident trends and an assessment of differences between dietary approaches.

Ethical Considerations: This paper is ethically sound by providing an accurate and objective account of existing research in accordance with ethical guidelines related to providing accurate views of the data, no contrived data or intentionally untrue statements were revealed. All sources were cited appropriately, and the work is original from the work of the research material. The analysis recognized and reported limitations of the included studies which are compatible with participants possibly having biases regarding self-reported data and that not all observational studies are not able to conclude cause and effect since they are cross-sectional.

Vegan Diets and Outcomes for Weight

Vegan diets cause substantial reductions in body weight and BMI. Meta-analyses of randomized controlled trials in healthy adults showed an average weight loss of 2.52 kg from a vegan diet, with a 4.10 kg average weight loss for individuals with overweight, obesity, or type 2 diabetes and a mean reduction in BMI of 1.38 kg/m² . In observational studies, mean BMIs were significantly lower in vegans compared to omnivores. These effects of vegans on weight and metabolism are likely due to the high fiber content of vegan diets. High fiber diets increase satiety and lower energy density, thereby decreasing total caloric intake.

Beyond weight, vegan diets are shown to improve cardiometabolic health, with improvements in insulin sensitivity (including HOMA-IR and fasting insulin), HbA1c in adults with overweight/obesity, or type 2 diabetes . Vegan diets also consistently have lower total and LDL cholesterol. While vegan diets have been shown to be nutritionally adequate, sometimes this means carefully planning a vegan diet prior to implementation , so among other nutrients, we want plausible attention paid to vitamin B12, vitamin D, iodine, selenium, calcium, and IRON, as clinical evidence can allow for fortification or supplementation of these nutrients in vegan diets.

High-Protein Animal-Based Diets and Weight Loss

High-protein animal-based diets (the carnivore diet) have been shown to be effective for short-term weight loss and fat mass. Meta-analysis of the carnivore diet in athletes showed that the average fat loss in the studies was 3.73% and weight loss was 4.57kg, with muscle mass outcomes either stable or slightly decreased (the average for all of the studies that were included in the meta-analysis was -0.33% for muscle mass). High-protein diets have higher satiety than higher carbohydrate diets (due to the thermogenic component associated with protein and the effects on appetite hormones, which lead to a lower caloric intake ). Long-term weight loss maintenance has been more difficult to gauge as studies have reported gains in weight at 12 months. The cardiometabolic effects of these diets are mixed, but improvements in triglycerides and blood pressure were noted . There are concerns about high saturated fat and sodium in these diets contributing to lower LDL cholesterol and potentially increasing the risk for cardiovascular disease in a few groups (especially red/processed meats). Observational studies consistently show an increased risk of global and abdominal obesity due to higher intake of animal protein, from meat, fish, and shellfish. Beyond the effects for obesity, high-protein animal-based diets are deficient in dietary fiber

Vegan and Animal-Based Diets Outcomes

Vegan and high protein, animal-based diets support weight loss in different means and different possible long-term health implications. Vegan diets benefit from a lower energy density, a higher fiber profile, and the beneficial effects on the gut microbiome that promote satiety and better metabolic efficiency. One consequence of pursuing a vegan diet is naturally limited caloric intake, and the associated weight loss is more likely to stick due to the substantial improvements in cardiometabolic health that accompany vegan eating.

High protein, animal-based diets take advantage of the satiating and thermogenic effects of protein. High protein, animal-based diets may help with short-term fat loss and preserving muscle mass (especially when coupled with some form of resistance exercise) but have serious challenges for long-term adherence and nutrition completeness in the format of a high protein, animal-based diet. Possible consequences include fiber deficiency and gut dysbiosis and higher contributions of saturated fat common in certain animal products may have harm on cardiovascular health. There are also some observational data suggesting a positive association of animal protein consumption with obesity risk.

Limitations

For research, methodological limitations complicate interpretations including: short study timeframes, difficulty adhering to dietary protocols in free-living conditions and large or vague dietary definitions for the comparison groups, which make direct comparisons and longer conclusions difficult. For any kind of dietary change, the quality of food in the quality categories is important. A diet that emphasizes whole foods and healthy plant foods in contrast to processed whole foods, whether vegan or animal-based will have very different results.

Conclusion

Both vegan and high-protein animal-based diets can result in weight loss but a well-structured vegan diet featuring whole, unprocessed plant foods has unique benefits — offering assistance with calorie control, carbohydrate quality, healthy gut, sustainable obesity prevention, and subsequent health outcomes. The multiple qualities lead to significant benefits for cardiometabolic health and gut health. High protein, animal-based diets, on the other hand, may be used as a tool for short-term weight loss (preferably under supervision) that adds a vital perspective on dietary habits, if you're careful in consuming lean, unprocessed proteins and pay close attention to nutrients always being complete by supplementation where necessary. Considering some kind of diet for obesity management, there is no question it has to be a diet that you can be consistent long-term, meets nutritional adequacy, and other healthy lifestyle considerations. Research going forward needs to focus on long-term, comparative studies, explore the unique effects of varying sources of protein, explore the interactions between diets and microbiome and metabolism, and develop strategies for long-term adherence to dietary regimes.

References

1. Kahleova, Hana, et al. "Effects of vegan diets on cardiometabolic health: A systematic review and meta‐analysis of randomized controlled trials." Journal of the American Heart Association, 27 Apr. 2022, PMC9540559.

2. "The Effect of the Carnivore Diet Under Calorie Restriction on Body Composition Changes in Athletes: A Systematic Meta-Analysis." ResearchGate, 12 Sep. 2024.

3. "How to Follow a Balanced Macro Vegan Diet." Coach My Macros.

4. "Assessing the Nutrient Composition of a Carnivore Diet: A Descriptive Study." Nutrients, 2024.

5. "How Protein Can Help You Lose Weight." Healthline.

6. "Plant-Based Diets: A Review of Their Impact on Body Composition and Cardiometabolic Health." Journal of the American College of Cardiology, 26 Nov. 2019.

7. "The potential impact of animal protein intake on global and abdominal obesity: Evidence from the Observation of Cardiovascular Risk Factors in Luxembourg (ORISCAV-LUX) study." Public Health Nutrition, 22 Jan. 2015.

8. "The Carnivore Diet: Healthy Trend or Risky Fad?" News-Medical.Net.

© 2026 Hannah Perez. All rights reserved.