Is eating one meal a day beneficial for body physiology?

Is One Meal a Day Good for Body Physiology?

Eating one meal per day is not recommended for most individuals, as it lacks sufficient evidence for long-term safety and may increase cardiovascular mortality risk, particularly when the eating window is restricted to less than 8 hours daily. 1

Evidence Against One Meal Per Day

Cardiovascular Mortality Concerns

• Eating windows shorter than 8 hours per day have been associated with higher cardiovascular disease mortality risk, making extremely restrictive one-meal patterns potentially dangerous 1
• The American College of Cardiology and European Society of Cardiology recommend an 8-12 hour eating window as safer than more restrictive regimens based on cardiovascular mortality data 1
• Extended fasting periods may particularly increase cardiovascular mortality risk in individuals with existing medical conditions such as cardiovascular disease, diabetes, or metabolic disorders 1

Adverse Physiological Effects

• A controlled trial in healthy, normal-weight adults consuming one meal per day showed significant increases in blood pressure, total cholesterol, LDL-cholesterol, and concerning elevations in hunger despite weight maintenance 2
• The same study demonstrated significant decreases in cortisol concentrations, suggesting disruption of normal hormonal patterns 2
• One meal per day resulted in modest reductions in fat mass but came with unfavorable changes in cardiovascular disease risk factors 2

Nutritional Adequacy Concerns

• Consuming all daily calories in a single meal makes it extremely difficult to meet nutrient requirements and maintain diet quality 3
• Nutritional deficiencies can lead to intellectual impairment, poor growth, degenerative diseases, and higher morbidity and mortality 3
• Multiple eating occasions throughout the day allow for better distribution of nutrient-dense foods including fruits, vegetables, whole grains, lean proteins, and dairy products 4

Limited Potential Benefits

Short-Term Metabolic Changes

• One study in lean individuals showed that eucaloric one meal per day (consumed between 5-7 PM) lowered body weight by 1.4 kg and fat mass, while increasing exercise fatty acid oxidation without impairing aerobic capacity 5
• However, this was an 11-day study in healthy lean individuals, far too short to assess long-term safety or sustainability 5

Time-Restricted Eating vs. One Meal Per Day

• The metabolic benefits attributed to time-restricted eating (8-12 hour eating windows) should not be conflated with one meal per day patterns 1
• Well-timed eating with 8-10 hour eating windows can enhance fat loss, reduce oxidative stress, and improve cardiovascular endpoints—but this typically involves 2-3 meals within that window, not a single meal 4, 1

Evidence-Based Recommendations

Optimal Eating Patterns

• A variety of eating patterns are acceptable for health management, but they should emphasize multiple meals with nutrient-dense foods 4
• The American Diabetes Association guidelines explicitly state there is no single ideal dietary distribution, but meal plans should be individualized while maintaining nutritional adequacy 4
• Mediterranean-style diets have stronger evidence for long-term health benefits compared to extended fasting regimens 1

Practical Meal Frequency Guidance

• Time-restricted eating with an 8-12 hour eating window provides metabolic benefits while maintaining safety 1
• This typically translates to 2-3 meals per day within the eating window, not a single meal 4
• For adolescents specifically, a self-selected 8-hour eating window (such as 11 AM-8 PM) is more appropriate than restrictive protocols 1

Key Dietary Priorities (Regardless of Meal Frequency)

• Emphasize nonstarchy vegetables (3 servings/day), fruits (3 servings/day), whole grains (3 servings/day), nuts/seeds (4 servings/week), and fish (2+ servings/week) 4
• Minimize refined grains, added sugars (no more than 1-2 servings/day), processed meats (no more than 1 serving/week), and sugar-sweetened beverages 4
• These nutrient targets are extremely difficult to achieve in a single daily meal 6

Critical Caveats and Contraindications

High-Risk Populations

• Individuals with cardiovascular disease, diabetes, or metabolic disorders should avoid one meal per day patterns due to increased mortality risk 1
• Those with a history of eating disorders should be particularly cautious, as extreme meal restriction may trigger disordered eating patterns 1, 6
• Patients with acute coronary syndrome, advanced heart failure, or recent cardiovascular procedures should not attempt any form of extended fasting 1

Potential Complications

• Small frequent meals may be clinically indicated for patients with early satiety, gastrointestinal symptoms, or postprandial hypotension—the opposite of one meal per day 6
• One meal per day may cause unwarranted weight changes, suboptimal nutrition quality, sleep disturbances, and limited nutrient distribution throughout the day 6
• The significant increase in hunger reported with one meal per day raises concerns about long-term adherence and potential for binge eating 2

Clinical Bottom Line

The current evidence does not support one meal per day as a beneficial eating pattern for body physiology. While short-term studies show some metabolic adaptations, the cardiovascular mortality concerns, unfavorable lipid changes, and practical difficulties in meeting nutritional needs outweigh any potential benefits 1, 2. Time-restricted eating with 2-3 meals within an 8-12 hour window represents a safer, more evidence-based approach for those interested in meal timing strategies 1.