Is skipping breakfast for intermittent fasting bad? The surprising truth

According to a 2019 review, recommending breakfast for weight loss in adults requires caution. The question of 'Is skipping breakfast for intermittent fasting bad?' depends on several factors beyond just the meal itself, including overall diet and individual health.

Quick Summary

The health impacts of skipping breakfast as part of intermittent fasting are highly individual. While some experience benefits like weight loss and improved metabolic health, others face side effects such as fatigue and nutritional gaps, with timing and food quality being critical factors.

Key Points

• No one-size-fits-all answer: The impact of skipping breakfast for IF depends on the individual's health, lifestyle, and how they feel.

• Metabolism is not 'jump-started': The total daily calorie intake, not meal timing, is the primary determinant of metabolic rate.

• Potential for nutrient deficiencies: Missing a meal increases the risk of lower intake of essential vitamins and minerals if not properly compensated for later.

• Circadian rhythms may matter: Research suggests that eating earlier in the day might offer greater metabolic benefits compared to eating later, but may be less convenient.

• Certain groups should be cautious: Children, pregnant women, diabetics, and those with a history of eating disorders should avoid or seek medical advice before skipping breakfast.

• Success depends on overall diet: The key to healthy IF is a nutrient-dense diet during the eating window, not simply skipping a meal.

The Traditional Breakfast Myth vs. Intermittent Fasting

For decades, the common wisdom was that breakfast was 'the most important meal of the day,' a myth often traced back to advertising campaigns and observational studies. However, randomized controlled trials have provided a more nuanced picture, revealing that the benefits associated with breakfast eaters are often correlated with healthier lifestyle habits overall, rather than the meal itself. Intermittent fasting (IF) challenges this notion by intentionally restricting the eating window, and for many, this naturally involves skipping breakfast. The most popular form, the 16:8 method, involves a 16-hour fast often achieved by extending the overnight fast until lunchtime. This deliberate breakfast-skipping strategy aims to reduce overall calorie intake and promote metabolic changes, such as increased insulin sensitivity.

Does skipping breakfast slow your metabolism?

A common fear is that skipping breakfast 'slows down' your metabolism. This is a persistent myth not supported by robust evidence. Your metabolic rate is influenced by your total daily caloric intake, not the timing or frequency of your meals. For many, skipping breakfast simply means they consume fewer calories throughout the day, which can aid in weight loss. The thermic effect of food (calories burned during digestion) is based on the total calories consumed, not when they are consumed.

Potential Risks of Skipping Breakfast

While not inherently bad, skipping breakfast can carry risks, particularly if done without proper attention to nutrition and overall health.

Impact on blood sugar and insulin

For individuals with pre-existing conditions like type 2 diabetes, skipping breakfast can lead to higher blood glucose spikes after later meals and impaired insulin responses. In healthy individuals, temporary drops in blood sugar can cause side effects like headaches, irritability, and difficulty concentrating. There is also evidence that habitually skipping breakfast can lead to decreased insulin sensitivity over time in some individuals, underscoring the importance of consulting a doctor.

Nutritional deficiencies

Skipping an entire meal can make it harder to meet your daily nutritional requirements. Studies show that habitual breakfast skippers often have lower intakes of key nutrients like folate, calcium, iron, and several B and C vitamins. It is crucial for those practicing IF to consume a nutrient-dense diet during their eating window to compensate for the missed meal.

Energy levels and mood swings

For some, fasting can cause irritability, fatigue, and lower energy levels, especially in the initial stages. While many adjust over time, this can negatively impact mood and concentration. However, studies show that some people experience increased self-control and pride during fasting periods, suggesting the psychological impact is complex and individual.

Benefits of Intermittent Fasting (Which May Involve Skipping Breakfast)

For many, IF offers a simple, effective approach to weight loss and improved metabolic health.

• Promotes weight loss: By restricting the eating window, IF naturally leads to a reduction in overall calorie intake, which is the primary driver for weight loss. Studies show IF is effective for weight management, comparable to other dieting methods.
• Improves insulin sensitivity: Reducing the eating window gives the body a break from constantly processing food, which can improve insulin sensitivity and help regulate blood sugar levels.
• Cellular repair and autophagy: Extended fasting periods can trigger autophagy, a process where the body cleans out damaged cells and regenerates new ones. This has been linked to potential benefits for longevity and protection against disease.
• Boosts brain health: Animal studies suggest IF can increase brain-derived neurotrophic factor (BDNF), a hormone that promotes the growth of new nerve cells and protects against certain neurodegenerative diseases.

Comparison: IF with Breakfast Skipping vs. Traditional Breakfast

Feature	Skipping Breakfast (Common in IF)	Traditional Breakfast Eaters
Timing	Fasting period extends into the morning, eating window often starts around noon.	Breaks the overnight fast early in the morning, typically within an hour of waking.
Calorie Intake	Often results in a natural reduction of total daily calories, aiding weight loss.	May increase total daily calorie count, especially if choices are unhealthy.
Metabolic Effect	No inherent 'slowdown.' Calorie burn depends on total daily intake.	Does not 'jump-start' metabolism; daily intake is the key factor.
Nutrient Impact	Higher risk of missing key nutrients if later meals aren't well-planned.	Offers an early opportunity to ingest essential vitamins and minerals.
Blood Sugar	Can cause initial drops and later spikes in blood glucose, especially for those with insulin resistance.	Can help stabilize blood sugar levels throughout the morning, depending on meal composition.
Personal Preference	Convenient for those not hungry in the morning or with busy schedules.	Preferred by those who feel hungry early or need sustained morning energy.

Who Should Avoid Skipping Breakfast?

While IF can be a healthy option for many adults, it is not suitable for everyone. Certain groups should avoid skipping meals or consult a healthcare provider before starting IF:

• Individuals with diabetes or blood sugar regulation issues: Fasting can cause dangerous blood sugar fluctuations.
• Pregnant or breastfeeding women: Nutrient needs are higher during these periods.
• Children and adolescents: Growing bodies require consistent energy and nutrients.
• People with a history of disordered eating: Fasting can be a trigger for relapse.
• Athletes with high-intensity training: Fasted workouts can impair peak performance, and nutrient timing is crucial for recovery.
• Older adults: May increase risk of muscle loss and require more consistent nutrient intake.

Conclusion: Is Skipping Breakfast for Intermittent Fasting Bad?

Ultimately, the question of whether skipping breakfast for intermittent fasting is bad has no universal answer; it is highly dependent on the individual. The overall quality of your diet, your specific health status, and how your body responds to fasting are all critical factors. Observational studies linking breakfast skipping to negative health outcomes often fail to account for confounding lifestyle factors, while modern RCTs show that for healthy adults, the timing of meals is less important than total caloric intake and nutritional adequacy. For those who find it convenient and feel good practicing IF by skipping breakfast, it can be a sustainable weight management and health-promoting strategy. However, for individuals who experience negative side effects or belong to a higher-risk group, eating a healthy breakfast and finding an alternative approach to managing calorie intake is a better option. Listen to your body and consult a healthcare professional to determine the best path for your unique needs. You can read more about the scientific consensus on breakfast and weight loss in this review: Effect of breakfast on weight and energy intake: systematic review and meta-analysis of randomised controlled trials.

Frequently Asked Questions

Is it bad to skip breakfast every day for intermittent fasting?

It is not inherently bad for healthy adults. The health effects depend on overall diet quality and how your body responds. For many, it's a sustainable way to manage calorie intake, but for some, it can cause issues like mood swings or nutrient deficiencies.

Does skipping breakfast make you gain weight?

Not necessarily. Randomized controlled trials have shown that skipping breakfast does not automatically cause weight gain. Weight is primarily influenced by the total calories consumed versus expended. Some studies show breakfast skippers consume fewer calories overall.

Can skipping breakfast affect my energy levels?

Yes, it can. Many people experience lower energy, fatigue, and irritability initially as their body adjusts to fasting. However, these side effects often diminish over time as the body becomes more efficient at using fat for energy.

What are the biggest risks of skipping breakfast?

The risks include potential blood sugar fluctuations, especially for diabetics; an increased chance of nutrient deficiencies if not mindful of food choices; and temporary side effects like headaches and fatigue.

Is it better to skip dinner instead of breakfast for intermittent fasting?

Emerging research suggests that eating earlier in the day might offer better metabolic benefits due to alignment with circadian rhythms. However, skipping dinner can be more socially restrictive. The best approach depends on personal preference and lifestyle feasibility.

How can I make sure I get enough nutrients if I skip breakfast?

Focus on consuming nutrient-dense foods during your eating window. Prioritize whole foods, a mix of lean protein, healthy fats, complex carbohydrates, and plenty of fruits and vegetables to ensure you meet your daily nutritional needs.

Who should not try skipping breakfast for fasting?

Individuals with diabetes or other metabolic issues, pregnant or breastfeeding women, children, adolescents, and those with a history of disordered eating should avoid it.