Most people would agree that not eating before bed, limiting carbohydrates, and sticking to small meals are part of a sound weight loss strategy. Most people are dead wrong. Here’s why.
Why it Matters
The most common weight loss approaches -- like not eating before bed, limiting carbohydrates, and sticking to small meals -- are not supported by science and are usually good only for short-term results.
- Meal timing and meal frequency both have little to no effect on weight loss and fat loss.
- Eating before bed has no demonstrable impact on weight loss and fat loss.
- Carbohydrates do not need to be removed to achieve fat loss and weight loss.
- Eating “clean” in order to lose weight and lose fat is a myth.
- Strength training (i.e. resistance training) should take priority over aerobic cardiovascular training (i.e. “cardio”) while dieting.
Most of the rules you’ve been taught for losing weight and fat are just not true. Here are five common myths that just won’t die.
Myth #1: Eating frequent small meals leads to greater weight and fat loss because it “boosts metabolism”
I'm sure you’ve been told that you should eat 5-6 small meals throughout the day in order to “boost your metabolism,” lose fat, and gain/retain lean mass and muscle. Well, what if I told you that this advice comes from a single study that has been controverted by a multitude of other studies?
Before we dive into the research, a quick primer on “metabolism.”
What does “metabolism” mean? If we were to discuss metabolism in its entirety, it would require hours of reading to understand the interplay between the hormonal and digestive systems in your body -- and that’s just for starters.
To simplify, for the purposes of understanding how it relates to food, weight loss, and diet: Our body requires energy for every bodily function -- from breathing, to thinking, to eliminating waste -- and to physically mobilize, from scrolling on your iPhone screen to exercising intensely.
The energy needed to sustain basic life functions at rest (i.e. thinking, breathing, etc.) is called Basal Metabolic Rate (BMR). The energy needs of BMR is measured in calories. This excludes everything else that one might do during the day, including the mere act of getting out of bed.
Because we don’t just lay at rest all day, the body obviously has additional energy (calorie) needs. Aside from the energy needed for basic activity and exercise, is the energy needed to digest food, which is called the “thermic effect of feeding.” Basically, it requires calories to process calories (food).
So, does food “boost” your metabolism? Yes -- but barely, and most certainly not enough to make you lose weight.
So where did this metabolism boosting myth start?
A study in 1993 demonstrated an increase in post-meal thermogenesis from eating four small meals compared to one larger meal (1). Due to this and other studies, the faulty belief that small frequent meals are advantageous to boosting metabolic rate was born -- the myth that if you eat more frequently, you burn more calories.
There’s a problem with this approach, however: When the entire day’s metabolism (metabolic rate) is measured instead of just the momentary increase after a meal, there is relatively no difference.
In other words, let’s say that your body -- regardless of when you eat -- will require an average of 100 units of energy per hour, for 2400 total units per day. We can expect that we won’t see this energy expenditure at a steady 100 units per hour; we will see an increase in energy need depending on what is happening. Walking will increase the number; sitting may decrease it. And eating will definitely momentarily increase it.
BUT, using this example:
- The increase (energy need) we would see from eating on any day would be 10-15%, or 240-360 units.
- Assuming you are still eating the quantity of food you need, regardless of when you eat it, the energy need would remain the same.
- Meaning if you only eat once per day, you will need about 240-360 units to digest the food -- and if you eat 10 times per day you will need about 24-36 units of energy each time.
So while it is true that if you ate more frequently, the number of times that the energy needed (your metabolism) would increase -- the actual number of units (calories) would not!
Back in 1982 researchers found no difference in energy expenditure (i.e. metabolism) between groups eating two versus six meals per day, with identical macronutrient and caloric intakes (2).
To reiterate, this means that eating frequently has no appreciable effect on your metabolism.
With the metabolism element addressed, let’s turn our focus to meal frequency’s impact on body composition.
Ample evidence-based data has been released confirming that meal frequency has no significant difference on body composition, with subjects eating between eating 3 to 6 meals a day (3).
And a 2015 meta-analysis concluded that meal frequency did not significantly affect total body weight change.
A single study conducted in 1996 is responsible for the “small-frequent-meals myth.”
This study found that higher meal frequencies were associated with greater losses of fat mass and greater retention of lean mass. However, again, these findings come from a single study that's over twenty years old. And, more so, removal of that study eliminates any effects of meal frequency on body composition (4) because all other studies are legion on the matter.
This means that meal frequency doesn’t affect your body fat or lean mass (e.g. muscle) levels.
So what should you do?
(1) Do what works and don’t obsess over the number of meals or their frequency
Find the pattern that works best for you and your lifestyle.
At lower meal frequencies, the tendency to go hungry between meals may be increased and you may affect your ability to be consistent. At higher meal frequencies, small meals may leave you unsatisfied and overly focused on food.
If eating more frequently helps your hunger levels and helps you stick to your calorie deficit, then by all means, go for it. But if it becomes more of a chore than anything, you can just as easily eat 2-3 meals a day and achieve the same results if your calorie and macronutrient needs are met. This ultimately comes down to personal preference.
(2) Know your calorie and macronutrient requirements per day for your goals
Above all else, eating the accurate amount of calories and macronutrients for your weight and fat loss goals is crucial. So long as you hit these targets, it does not matter in how many meals or when these meals are consumed.
For example, if your daily protein target is 160-200g, it may be difficult to eat all your protein in just two meals, especially since protein is highly satiating. For reference, 80-100g of protein is 2-3 very large pieces of chicken breast. So in this case, more meals might be a better option.
Myth #2: Eliminating Carbs is Necessary for Weight Loss
The story goes something like this. You or someone you know cut out carbs and lost 5lbs in their first week! Amazing!
Only the weight lost likely came from water, not from fat.
Carbohydrates are stored in the body as glycogen. 1g of glycogen stores 2.7g of water, so when carb intake is reduced and in turn, glycogen stores are reduced, water weight is lost.
If you've had success on a low carb diet it's possible that by cutting out an entire macronutrient, you thereby reduced your overall calorie intake.
So should you cut carbs when trying to lose weight? The answer here is it’s highly individual and up to you. Research demonstrates when protein is high, low carb or low fat diets are equally effective for fat loss and muscle retention (6).
How about insulin though?
Insulin is an anabolic hormone that spikes after feeding and promotes storage of nutrients in tissue. Insulin gets a bad rap and is often to blame in the fitness community for fat and weight gain.
The belief is that since carbohydrate intake spikes insulin and insulin promotes fat storage, then reducing carb intake will lead to fat loss. Except this isn’t the case.
In fact, when obese adults are in a calorie deficit, higher carbohydrate diets result in more total body fat loss than lower carbohydrate diets, when calories are matched (7).
An exception to the rule would be for obese, sedentary individuals with extreme insulin resistance. These individuals will likely benefit from a low carb, high fat diet, until insulin resistance is improved (8).
Additionally, insulin has an inhibitory effect on cortisol, a stress hormone that is increased during periods of dieting and causes a breakdown of proteins in the body to glucose, including muscle tissue.
In other words, while dieting, consuming carbohydrates to stimulate insulin production can help limit the amount of muscle mass lost.
In healthy men, when fat and calories are matched, higher carb diets resulted in lower cortisol levels and higher testosterone levels compared to a diet lower in carbohydrate and higher in protein (9).
Higher carb diets may result in less circulating stress hormones in the body.
Another study, which analyzed the effects on carbohydrate intake in combination with training, found that lower carbohydrate intakes led to a significant decrease (-43%) in the free testosterone to cortisol ratio (a marker of training stress) after three days of intensive training (60 mins at 70-75% vo2 max) compared to the control (10).
Lower carbohydrate diets in conjunction with intensive training leads to greater markers of systemic stress.
Another reason to consider keeping carbohydrates in your diet is their performance benefit. Assuming you’re doing resistance training along with your calorie deficit, then it's important to note that carbohydrates are the predominant fuel source for anaerobic exercise like weight training.
Research demonstrates that lower carb intakes negatively impact strength training performance and endurance, perhaps due to glycogen depletion in the working muscle (11,12,13).
So what should you do?
Weight loss ultimately comes down to calories in, calories out and diet is highly individualized. Once the protein target is met, the ratio of fats to carbs doesn’t really matter so long as you're in a calorie deficit (comes down to your personal preference and what foods you enjoy eating, how you feel and function on different ratios).
In terms of optimal health, food selection does matter when choosing carbohydrates, and not all carbohydrates are created equal. Eating a wide array of fruits and vegetables, oats, rice, whole grains, quinoa is the way to go. But there's no harm in having some pasta or the occasional sweet either, so long as you’re eating enough fiber and within your calorie targets.
It’s also perfectly fine to choose a high fat, low carb diet, which allows some people to perform better.
Find what works for you.
Myth #3: You have to eat “clean” to lose weight
This might sound redundant by now, but weight loss ultimately comes down to calories in versus calories out. When speaking strictly about weight loss, not total health, the body doesn’t know the difference between a calorie from refined white sugar and from fruit. 1g of carbohydrate yields 4 calories, whatever the source.
Here’s an example to put things in perspective. An individual sets a goal to lose 10lbs this year and eat healthy. “I’ve been eating clean and healthy and haven’t lost any weight. I must have a slow metabolism.” I hear this time and time again from clients and the reason is quite simple.
They are eating too much.
If 3500-3700 calories equates to one pound of fat/tissue loss, then to lose 1lb of weight per week you would need to be in a calorie deficit of 500 calories per day.
They get rid of all sweets and processed foods. Awesome. It’s 9pm and they’re hungry for a snack. They reach into the cabinet and grab some natural almond butter because almonds are full of healthy unsaturated fats. Love that. Except little do they know that a true serving is two level tablespoons, and who in their right mind levels off their almond butter? So they scoop two large spoons into their mouth and eat 400-500 calories. There goes the deficit for the day.
Chicken breast can easily have well over the estimated calorie count when cooked in an abundance of olive oil. Bottom Line? Healthy foods will cause weight gain when eaten in abundance.
Another factor to consider is that most people tend to underreport and underestimate how much they’re eating (14).
In my experience, individuals tend to also overestimate how much they are burning during workouts.
So before the assumption is made that an individual has a faulty or slow metabolism, it may be more likely that they are in fact eating too much.
Aside from the weight loss perspective, is clean eating actually healthier?
In the sport of bodybuilding, eating clean is highly popularized. The methodology of eating clean implies healthy foods, abundant in micronutrients (vitamins, minerals).
Except some research demonstrates an opposite result.
Analysis of the monotonous, repetitive diet of elite bodybuilders diets revealed certain micronutrient deficiencies, including Vitamin D in males, and calcium, copper, and chromium in females (15).
This discovery is not isolated to just bodybuilding. When menus from popular specialized diets are analyzed, (Atkins, South Beach Diet, and DASH diet) they were found to be deficient in micronutrients (16).
It’s possible that by trying to eat ultra “clean” or healthy all the time, the body is in fact deprived of certain nutrients due to the occlusion of particular foods or food groups from the diet. If a “clean” eating diet is going to be followed, ensure a wide range of foods are eaten to ensure adequate micronutrient intake.
Part of the reason restrictive diets tend to lead to negative long term outcomes is due to the restriction binge cycle. Thinking of foods as good and bad instead of as more or less nutrient dense, can lead to negative psychological views around food.
Just like one healthy meal won’t make you extremely healthy, one “less nutrient dense” meal won’t ruin your health. Patterns over time that matter most.
So if eating one cookie during your diet will help you stick the course, then by all means go for it.
Myth #4: Eating before bed makes you gain weight
Contrary to popular belief, your body doesn’t have some magical sensor that once the clock hits 8pm, your body stores carbs as fat. This just isn’t true. Let’s look at the research.
Does metabolic rate drop during sleep?
The idea that eating before bed makes you gain weight partly comes from the belief that your metabolic rate drops as you sleep.
What researchers found to be true is that although Basal Metabolic Rate drops during the first half of your sleep, it actually increases in the second half of sleep, believed to be due to an increase in REM activity (17).
Overall, metabolic rate while asleep is similar to that when awake and in non-obese subjects, sleeping metabolic rate was actually found to be higher than resting metabolic rate (18,19).
By this logic, then so long as the snack or meal you’re eating fits within your calorie target for the day, then there is no reason it would hinder weight loss.
How about carbs before bed?
A concern specifically about eating before sleep is that all carbohydrates will be stored as fat.
A study actually found the opposite to be true.
When controlled for calorie and macronutrient intake, the group eating a higher percentage of their carbohydrates before bed (80% of daily intake) had more weight loss, body fat reduction, and reported less hunger than the control group (20).
In addition, eating carbs before bed may even make you sleep better due to carbohydrates' effect on increasing serotonin, which is an important neurotransmitter that regulates sleep.
Since your metabolic rate does not decrease when you sleep, there is no negative consequence of eating before bed on weight and fat loss.
If you’re in a calorie deficit and trying to lose weight, just make sure the meal fits within your calorie and macronutrient targets for the day. Instead of fixating on each individual meal/specific food for weight loss, focus on how it fits within the entire structure of your routine.
Are there individual differences to eating before bed?
It’s important to note that some individuals report a disturbance in sleep quality when eating too close to bedtime. (21)
Since small changes in sleep quality and duration (even less than an hour) can result in less fat loss during a calorie deficit, it may be wise to experiment and figure out if eating before bed affects your sleep. (22)
Myth #5: You need to do cardio to lose weight
For optimal health, aerobic exercise should be done regularly, and this section is not to discredit that fact.
Cardiovascular exercise has vast health benefits, some of which include reducing blood pressure, lowering resting heart rate, decreasing stress, improving brain function, and so on (23).
However, when it comes to weight loss, the goal is to lose fat, not muscle. Since a primary factor affecting the body’s metabolic rate is the amount of lean muscle mass, it is highly beneficial to preserve as much as possible during a deficit (24).
When dieting, the body will break down both fat and muscle for fuel. To minimize the amount of muscle lost, resistance training along with a high protein intake is key.
So when should cardio be implemented in a weight loss regimen?
As the diet progresses and an individual's metabolic rate slows, the amount of weight loss may also consequently be reduced. Rather than decreasing food intake further in order to create an additional deficit, cardiovascular exercise can be utilized to create this deficit. Thus, cardio becomes a strategy to create an additional calorie deficit on top of a resistance training regimen and well structured diet to successfully lose weight and lose fat.
Once the weight is lost, the goal is to keep it off, which a large majority of people struggle with.
A meta-analysis of 29 long-term weight loss studies revealed that “more than half of the lost weight was regained within two years, and by five years more than 80% of the lost weight was regained” (25).
Without going into too much of the science on why this happens, this highlights the importance of choosing a diet that you can adhere to in conjunction with consistent resistance training so the progress you make lasts for the long term.
What Actually Works for Weight Loss?
The goal of this article isn’t to bash certain methods of weight loss, but rather to shed some light on the truth.
Try not to get caught up with specific diets and individual food choices. Instead, develop a sound plan based on scientific principles and stick to it. Know why each choice is being made.
Here’s some general rules to follow.
Aim for 1lb of weight loss per week - the slower you lose the weight, the better. Depending on how precise you want to be, use formulas or test your metabolic rate in a lab. Estimate or track your NEAT, non exercise associated thermogenesis (any movement that isn’t exercise related, i.e. climbing stairs), and add this to your resting metabolic rate to determine your energy expenditure, minus exercise. Set up your macronutrients based on your goals.
Resistance train 3-6x per week and use cardio as an additional tool. If you’re not a competitive physique athlete, then it’s probably not necessary to track your macros everyday, but instead use it as a short term tool to learn portion sizes and how to make good food choices.
Over time, learn to rely more on internal cues such as hunger rather than external cues like macronutrient counting.
Using these guidelines and focusing on the big picture instead of on crash, extreme diets and instant gratification is the key to long term, successful weight and fat loss.
Andrew Malkiel, MSc
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