Most people assume that if you skip breakfast, your metabolism will decline, but this has not been shown to occur. The sum collection of the studies shows that breakfast consumption plays a minor to small effect on total energy balance and body weight changes. Therefore, the current research does not support a causal role of breakfast consumption in preventing obesity, but breakfast consumption may promote better insulin sensitivity
DOES INTERMITTENT FASTING RESULT IN BETTER WEIGHT LOSS ARTICLE SUMMARY
- Intermittent fasting is not associated with lean muscle mass losses.
- There are pros and cons of skipping breakfast.
- Intermittent fasting does not result in impaired metabolism.
- Having breakfast results in better insulin sensitivity compared to skipping breakfast.
- An intermittent fasting meal plan, ketogenic diet, fasting days, and keto-friendly intermittent fasting are all effective for reducing calories throughout the day.
9/15 UPDATE: INTERMITTENT FASTING TO LOSE WEIGHT: DOES TIMING MATTER?
For generations, it has been advocated that breakfast is the most important meal of the day, but according to a new study, this may not be true. Some studies have found greater weight loss when a big breakfast is consumed, suggesting that a big breakfast can provide a metabolic advantage compared to a larger number of calories consumed at dinner.(28, 29) This suggests that late-night eating can result in less weight loss despite consuming similar calories.
The latest rage in dieting is an intermittent fasting plan or some keto and intermittent fasting combined. The intermittent fasting diet plan/intermittent fasting keto diet involves a fasting window, usually 12 hours or more. Many people have to adjust to having an empty stomach for such a long time, but many swear about the health benefits. Some warn that intermittent fasting can lead to binge eating disorders and other body image disorders.
Some will fast on the weekend, so it’s two days per week of just water/broth. Other forms of intermitten fasting are alternate days fasting and the 16:8 intermittent fasting 7-day meal plan. The question is: Is there a best intermittent fasting schedule? Is it better to eat earlier or later in the day?
INTERMITTENT FASTING: SKIP BREAKFAST OR DINNER?
Some researchers have suggested that circadian rhythms are disrupted with late-night feedings, which can have a long-term effect on weight gain.(30) Researchers published in the journal of CELL METABOLISM that when calories are controlled and are similar, weight loss is the same regardless of whether the largest meal of the day is at breakfast or dinner.
THE STUDY
Researchers had subjects consume similar calories, except one group received their largest meal at breakfast, and the other group received the largest number of calories for dinner. The subjects completed a 4-week randomized crossover trial in which similar calories and macronutrients were consumed, comparing a big breakfast (45% calories consumed at breakfast, 35% calories consumed at lunch, 20% calories at dinner) versus a big dinner (20% calories consumed at breakfast, 35% calories consumed at lunch, and 45% calories at dinner).
Both diets provided the same nutrient composition (30%:35%:35% as protein: carbohydrate: fat). At the end of the study, both groups lost a similar amount of weight; however, the group that consumed their largest meal of the day at breakfast had increased satiety throughout the day compared to the group that consumed a big dinner.(31)
There was no metabolic advantage to consuming a big breakfast, as many proponents claim. There was no difference in metabolic rate between the two groups. However, the big breakfast group had greater increases in physical activity. This suggests that having more calories at breakfast can influence greater daily physical activity.
The big breakfast group had greater satiety and lowered hunger throughout the day compared to the group that had most of their calories at dinner, suggesting that consuming a larger number of calories at breakfast over a longer duration can lead to reduced caloric intake and greater weight loss.
ADAPTED FROM: Leonie C. Ruddick-Collins, Peter J. Morgan, Claire L. Fyfe, Joao A.N. Filipe, Graham W. Horgan, Klaas R. Westerterp, Jonathan D. Johnston, Alexandra M. Johnstone, Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity, Cell Metabolism, 2022,
INTERMITTENT FASTING OR EAT BREAKFAST
It has been widely suggested that breakfast is the day’s most important meal. Most large-scale studies regarding breakfast consumption and obesity have had conflicting results. Some have found that breakfast intake is associated with lower rates of obesity(1), but many other studies have found that skipping breakfast does not contribute to obesity.
The discrepancies in the studies on breakfast consumption are influenced by many factors, such as meal composition and size and, most importantly, the habitual breakfast behaviors of the subjects. If you are used to having breakfast and are forced to start skipping breakfast, this can significantly impact the study results.
PROS AND CONS OF SKIPPING BREAKFAST
BREAKFAST MEAL PREP FOR WEIGHT LOSS: THE CASE FOR BREAKFAST
The body has circadian rhythms, referred to as the body’s molecular clock. The circadian clock synchronizes internal metabolism with the environment, interacting with light-dark and feeding and fasting states. (2) Most people are familiar with the nighttime hormone melatonin, which is secreted by the brain about two hours before a person’s regular bedtime and increased with darkness and suppressed by light.
The circadian clock gene expression is not exclusive to the brain; it is widespread across multiple organs and tissues throughout the body, synchronizing neuronal and endocrine signaling.(3) For example, LPL activity (i.e., gatekeeper to fat storage in fat cells) exhibits 24 h variations throughout the day, being more active during times of feeding and less active during times of rest.(4)
Diurnal rhythms from light and dark exposure have numerous effects on biochemistry in the body. For example, daily core body temperature, heart rate, and blood pressure peak in the light or active phase and are lowest at dark or rest phase in humans.(5) In the realm of resistance exercise, studies have found greater increases in strength in the later afternoon versus the morning.
Despite these morning improvements, no greater increases in muscle mass have been observed.(6-8) The body also seems to have natural circadian rhythms for foods. For example, eating meals at regular meal patterns each day resulted in greater insulin sensitivity, appetite scores, and thermogenesis compared to eating similar calories but with irregular feeding patterns.(9)
INTERMITTENT FASTING BENEFITS
The benefits of intermittent fasting with meals eaten earlier in the day align with our body’s natural circadian rhythms. Whereas eating late at night seems to increase the risk of metabolic dysfunction. Shift work and airline personnel who suffer chronic jet lag are associated with health conditions such as the increased risk of obesity, type 2 diabetes, and cardiovascular diseases in epidemiological human studies.(10, 11) The association of skipping breakfast with cardiovascular and all-cause mortality events were found to be positively correlated compared with those that eat breakfast. (32)
IS IT BETTER TO SKIP BREAKFAST OR LUNCH?
Researchers have referred to the process of eating most of your calories in the earlier part of the day is referred to as Early Time-Restricted Feeding. Some have suggested that Early Time-Restricted Eating increases energy expenditure or may reduce overall food intake by reducing ghrelin levels. Still, there is much more research before a concise answer on whether calories consumed earlier in the day are superior for fat loss to calories consumed in the evening.
The importance of following the body’s natural circadian rhythms for food intake is a topic of intense debate known as chrono-nutrition. Some say for optimal health benefits, “Eat like a king in the morning, a prince at noon, and a peasant at dinner.” This means that most of your calories should be consumed in the morning, whereas fewer calories should be consumed in the evening. There is some research suggesting that skipping breakfast can cause weight gain.
EATING A BIG BREAKFAST AND SKIPPING LUNCH
Here are a few examples of differences in metabolic function when eating during the morning versus eating at night:
· A study found that when subjects were given the same calories, morning diet-induced thermogenesis (i.e., greater calories burned) was significantly higher than afternoon and night diet-induced thermogenesis.(5)
· In a study of 420 overweight/obese patients undergoing a 20-week weight-loss diet, those who ate their main meal later in the day lost significantly less weight than early eaters. Differences in caloric intake, macronutrient distribution, or energy expenditure could not explain the weight loss success of early eaters.(12)
· Participants received meals with the same calories at 8 am and 8 pm. The 8 am meal produced higher levels of the fat-burning hormones (epinephrine, norepinephrine) and lower levels of the stimulating hunger ghrelin than the same meal at 8 pm (13)
STUDIES CONT.
· A small study compared early time-restricted feeding. All calories were eaten during an 8-hour window between 6 am and 3 pm and fasting for the rest of the day to a time-restricted feeding group for more than 8 hours between 11:00 am and 10 pm and fasting for the rest of the day. Calories were similar between the groups, but the early time-restricted feeding group had greater changes in insulin sensitivity, fasting glucose, body mass, and body fat at the end of five weeks.(14)
· In one study, subjects lost more weight by eating a big breakfast in contrast to eating a big dinner. The “Big Breakfast Group” consumed (700 kcal Breakfast/500 kcal Lunch /200 Kcal Dinner) kcal in three daily meals, whereas the “Big Dinner Group” consumed calories in the reverse order (200 kcal Breakfast/500 kcal Lunch/700 kcal Dinner). Despite consuming identical calories at the end of the study, the big breakfast group lost more weight and inches around their waist.
The big breakfast group also had a greater decrease in fasting glucose, insulin, and insulin resistance, while reporting greater satiety, lower hunger, and concordantly lower ghrelin levels.(15) A similar study found that subjects who consumed most of their calories later in the day lost less weight and had slower weight loss despite similar caloric intake, energy expenditure, and sleep duration.(16)
HEALTHY BREAKFAST MEAL PREP
Many people are not hungry in the morning. In contrast, others love a big breakfast with foods such as scrambled eggs, breakfast bowls with peppers, breakfast burritos, overnight oats with chia seeds and peanut butter, egg muffins, and easy breakfast avocado toast. If you are a breakfast eater and looking for healthy meals, here are a few ideas for weight loss:
- Avocado Breakfast Recipes for Weight Loss
- Weight loss healthy egg breakfast
- Breakfast Protein Shake for Weight Loss
- Breakfast meal prep ideas for weight loss
- Grab and Go breakfast for weight loss
- Best Keto Breakfast for Weight Loss
- 7 Healthy Fats Breakfast Ideas
BREAKFAST MAY INCREASE NEAT
Consumption of breakfast is also associated with greater NEAT levels. NEAT stands for Non-Exercise Physical Activity. It is a measure of physical activity such as walking, doing chores, cleaning, etc. and is a significant source of burning calories over the day.
NEAT contributes to more calorie burning than exercise! Participants were randomized to consume breakfast daily or skip breakfast for 6 weeks. There was no decrease in metabolism, as commonly suggested by skipping breakfast.
There were no changes in body mass and adiposity between the groups at the end of the six weeks. However, those that consumed breakfast had greater physical activity, which resulted in a greater than 442 kcal/day burned thru more movement.
The breakfast group consistently engaged in more “light”-intensity physical activity during the morning than the fasting group. Despite the skipping breakfast group eating fewer calories, the breakfast group moved around more, which resulted in greater total energy expenditure for the day.(17) Other studies have reported similar findings that breakfast consumption increases physical activity levels in the morning.(18-20)
Interestingly, obese people do not have the same increases in physical activity after breakfast consumption compared to lean people, but they do have a small increase in physical activity.(21) The totality of the evidence that consuming breakfast for increasing physical activity has mixed results, and more studies need to be conducted.
SKIPPING BREAKFAST BENEFITS: THE CAST AGAINST BREAKFAST
Based on the few studies mentioned above, you may be tempted to eat more in the morning instead of the evening. Most time-restricted eating skips breakfast and has lunch and dinner. Many question whether it is okay to skip breakfast for intermittent fasting. Does this mean that eating later is ineffective for weight loss?
Absolutely not! For example, a meta-analysis of 30 studies on the research of people fasting for Ramadan (i.e., not eating from sunup till sundown) found significant reductions in body weight.(22, 23) Other studies examining the religious practice of the Baháʼí Faith, which fast from sunrise to sunset, also resulted in a significant reduction in body weight and body fat. This means skipping breakfast to lose weight works for those that don’t like breakfast. Check out the skipping breakfast to lose weight reddit thread.
Intermittent Fasting Studies
The debate about whether eating in the morning or evening was superior for weight loss was best summed up in a review by Dote-Montero et al. in a paper titled “Effects of Intermittent Fasting on Cardiometabolic Health: An Energy Metabolism Perspective,” the team of researchers concluded based on the sum of all the research to date on intermittent fasting concluded that time-restricted eating, regardless of the time of the eating window, does not appear to affect 24-hour energy expenditure acutely, but it may increase both protein and fat oxidation.
The study also mentioned several studies in which intermittent fasting can provide cardiometabolic health benefits independent of weight loss.(24) This was recently reconfirmed that early time-restricted feeding was compared to continuous dieting.
Results
Both groups consumed similar calories and had similar physical activity throughout the day. Both groups had similar weight and fat loss at the end of the study. Still, the early time-restricted feeding group had several metabolic benefits that the calorie-restriction group did not have.
The early time-restricted had improved insulin sensitivity and greater nutrient uptake (i.e., glucose and amino acid uptake) in muscle independent of body composition changes or energy expenditure. The simple change of eating earlier led to a ~400 kcal deficit.
The author stated that early time-restricted feeding led to a natural reduction in calories without the need for tracking calories throughout the day.(25) Researchers from the renowned Pennington Biomedical Center found that early time-restricted feeding did not affect 24 energy balance, but it reduced ghrelin levels and resulted in greater appetite suppression.
They concluded that early time-restricted feeding results in weight loss thru reduced appetite rather than affecting energy expenditure.(26) Early time-restricted eating may be difficult as many people enjoy having dinner with the entire family after work. Still, the preliminary evidence is promising on the metabolic effects of eating earlier in the day instead of later.
IS THERE A BEST TIME TO SKIP MEALS FOR WEIGHT LOSS?
Most people assume that if you skip breakfast, your metabolism will decline, but this has not been shown to occur. The sum collection of the studies shows that breakfast consumption has a minor effect on total energy balance and body weight changes. Therefore, the current research does not support the causal role of breakfast consumption in preventing obesity, but breakfast consumption may promote better insulin sensitivity. (27)
KEY POINTS
- Whether you skip breakfast or not does not seem to result in differences in weight loss or fat loss.
- Intermittent fasting does not result in impaired metabolism.
- Intermittent fasting is not associated with lean muscle mass losses.
- Having breakfast results in better insulin sensitivity compared to skipping breakfast.
An intermittent fasting meal plan, ketogenic diet, fasting days, and keto-friendly intermittent fasting are all effective for reducing calories throughout the day.
REFERENCES
2. Panda S. Circadian physiology of metabolism. Science. 2016;354(6315):1008-15.
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