Dieting Demystified: Diets That Work
Updated: Jun 8, 2020
Everyone and their mother seems to understand nutrition. People think just because they have a fork at home they can tell you what to eat, where to eat, and how to eat. Truth is nutrition isn't something you magically pick up because you watch cooking shows, nutrition is actually a field of science.
What does this field tell us? It tells us nutrition is complicated and how each of us eat depends on multiple different factors.
Many people try to oversimplify the subject by imposing a supposed 'problem' leading to all of your issues. Some people demonize carbs, meat, dairy, fat, or diets in general while others praise these same things. It's very difficult as an ordinary person to separate fact from fiction. So many dieting books with conflicting information from people without clear expertise in nutritional science (1). So let's go over what diets actually work and some of what the science has stated regarding this issue.
A great number of these books are geared towards weight loss as this fits into the obesity epidemic. Obesity is a notable public health issue with a prevalence of about 40 percent in the United States alone (2). Obesity is associated with poor health outcomes (3) so it makes sense many interventions are targeted at this growing demographic.
Obesity is a complex and multi factorial disease so it's beyond the content of this blog to explain that in its entirety currently (4). Just know many books surrounding nutrition, also nutrition information in general, target specifically weight loss for reasons mentioned and other reasons.
People could also follow particular diets to gain weight, maintain weight, or achieve some sort of health outcome. However, the biggest question on everyone's mind is... which diet is best?
Energy Balance and Calories
Perhaps the better question would be, why do diets work? It's simple many diets work in the context of weight loss, gain, or maintenance not due to magic but because of energy balance. Energy balance is based on fundamental thermodynamics which states energy cannot be created nor destroyed but gained, lost, or maintained (5). Energy balance is maintained when energy intake equals energy expenditure. This energy intake and expenditure is measured by the heat unit calories but the calories you see on food labels isn't the same it's actually measured in kilo-calories (6). Kilo-calories or Calories (capital C) stands for the amount of heat needed to raise the temperature of 1 kg of water from 0 to 1 degrees Celsius (6).
Like previously mentioned energy intake and energy expenditure are measured in calories so we often refer to energy balance as “calories in vs calories out” (CICO). So energy intake refers to calories in and energy expenditure refers to calories out (7). I’ll talk about energy balance and CICO simultaneously since they're practically the same concept.
This is NOT the same thing as calorie tracking because calorie tracking refers to estimating your energy needs from a mathematical model and using a method to track calories on food packaging based off of that model.
Losing weight based off of the CICO model requires an individual to be in a caloric deficit, this means consuming less calories than is needed to maintain their current weight. In order to gain weight a person must be in a caloric surplus so they must consume more calories than is needed to maintain their current weight (7).
An analogy I would like to use would be a balloon. Imagine if airflow in (caloric intake) is balanced with airflow going out (caloric expenditure) to keep the amount of air inside a balloon relatively stable this would be a balance of airflow (caloric maintenance). If more airflow goes into the balloon than what goes out the balloon gets bigger, this concept can be applied to the body where in a caloric surplus we can gain muscle or fat. If more airflow leaves the balloon than what goes in the balloon gets smaller, applying this to the body in a caloric deficit means we can lose muscle or fat. Notice this is an analogy to get you to understand the concept, metabolism is way more complicated than this example but this is the basic premise of CICO.
I’m sure the main concern many of you may have would revolve around the idea you have to track calories to lose weight. While calorie tracking is a good method for some it doesn’t work for many other people, CICO is also not the same as calorie tracking. All diets that help you lose/maintain/gain weight have to abide by energy balance (8). There are multiple factors that could affect energy balance and one of these factors is macronutrient composition. This will probably warrant a separate post on the subject.
Macronutrients or macros are nutrients your body needs larger amounts of to maintain bodily function. There are three kinds of macronutrients: protein, carbohydrates, and fat (9). Let's talk about the basics of each.
Protein in a nutshell is a chain of amino acids. It is essential for many bodily processes. Out of the three macros it has a very high satiety effect, meaning it makes you feel fuller more so than the other macros (10). It also has the highest thermic effect compared to other macros, thermic effect refers to the energy required to digest and absorb food (8).
Carbohydrates or carbs are compounds of carbon, hydrogen, and oxygen which form a variety of sugars. There are three major categories of carbs which are dietary fiber, sugars, and starches (10). There are sugars called monosaccharides like glucose and fructose, as well as other known sugars like disaccharides such as sucrose and polysaccharides like maltodextrins. Dietary fiber, which includes both soluble and insoluble fiber, are indigestible but have numerous health benefits associated with it, I’ll talk about this more later (10). Starches are made up of complex sugar molecules and are in a variety of foods we eat like potatoes. Keep in mind there are many misconceptions about carbs (11).
Dietary fat or fat is usually called lipid in the scientific literature and it is also made from carbon, hydrogen, and oxygen. The lipids we usually consume through diet are called fatty acids (FA) the way these fatty acids link together to form a chain determines if they’re saturated or unsaturated (10). Without getting too much into the chemistry saturated fats are in foods such as butter, animal fats, and coconut oil. Unsaturated fats can break down into two variations one is monounsaturated fats in foods like olive oil, peanuts, pecans, and almonds. The other variation is polyunsaturated fat in foods like fish, flax seeds, and canola oil. Many fat sources contain a varying degree of saturated and unsaturated fats, ideally you want to consume more unsaturated fats in your diet than saturated fats for heart health (12).
I know the question might pop up about which amount of what you should consume. Of course the correct answer would be “it depends” as we all vary in our needs, circumstances, and histories. Good news is there are general guidelines that could be useful to you.
First, you might want to consider a high protein diet. Higher protein intake can have positive effects for those trying to lose weight, those trying to maintain muscle when resistance training, and depending on the sport/activity can have benefits for athletes (8, 13, 14). We should consume approximately 1 gram of protein per lb of body weight. We also have to remember protein quality also matters for things such as building muscle, we have to make sure we get all essential amino acids, essential because our body NEEDS them (13, 14).
Second, like I mentioned previously carbohydrates that are fibrous have many associated health benefits for many health conditions (19) so it’s wise to eat adequate amounts of it of course by consuming enough fruits and vegetables. The recommended daily intake is about 2 and a half cups of vegetables per day (20) and the recommended fiber intake varies from 28 to 36 grams per day. Of course these are general recommendations and might not apply to you. Athletes might need higher intake of carbs (14). I know what you are thinking but no other forms of carbohydrates that are not fruits or vegetables do not make you “fat” weight gain is due to caloric surplus (7, 8, 11).
Third, make sure to not over consume saturated fat. Guidelines for Americans are adamant that saturated fat be less than 10 percent of a person's total caloric intake (20). So hypothetically if you ate 2000 kcal in a day that's less than 20 calories. We know replacing saturated fat intake with polyunsaturated fat intake for the majority of fat intake can help prevent the development of heart disease (15). It might be nearly impossible to avoid saturated fat all together as different fat sources have various amounts but we should strive to lower our intake.
Notice there is no magical “macro split”, all of these are general guidelines that may or may not be useful to you. Depending on your goals you might want to apply some of this information to yourself, for your specific goals it might be better to work with a professional. Ideally we should eat higher protein, higher fiber, and less saturated fat. Yes, we can also all agree eating your fruits and veggies is important especially for those micronutrients.
Micronutrients in simple terms are vitamins and minerals. Proper vitamin and mineral intake is important for various reasons. Especially important for proper growth and development (17). Inadequate intake of these micronutrients is associated with various health defects and health complications (17). Complications like acute respiratory illnesses, inflammation, cognitive decline, certain types of cancer, and others (18, 20).
Well if these micronutrients are so important, what foods have them? It is abundantly clear the foods that have some of the highest concentrations of micronutrients are fruits and vegetables (20). Those who consume a primarily vegetarian diet have health markers associated with decreased risk of obesity, hypertension, diabetes, certain forms of cancer, and mortality (22).
I’m not stating you need to go fully vegan but part of the issue, especially for Americans, is the general low amount of intake for fruits and vegetables (21). Just to clarify, vegetarianism is not the same as veganism because vegetarians can consume animal products unlike vegans. You don’t need to go strictly vegetarian or vegan to gain many of the benefits mentioned you should just be eating more plants (20, 21, 22).
Fruits and vegetables are typically high in fiber as well which we know has numerous benefits associated with it (19). It’s also important to make sure we are eating a wide variety of fruits and vegetables because certain foods can have certain nutrients more than others (20).
I know you're probably thinking… if eating more fruits and vegetables has so many benefits… Why do we have issues like obesity in the first place?
We have to remember obesity is very complex just like many other chronic illnesses (4). There is no magic bullet solution to health. It is very complex and multi-factorial; there could be many biological, psychological, and sociological factors that aid in the development of obesity.
One issue that could potentially lead to the development of obesity are ultra processed foods. These foods are notoriously highly palatable and low satiating, meaning they are easy to overeat and don't make you feel as full. This can lead to a caloric surplus, which we know from earlier can lead to weight gain (16). For that reason we should aim to eat mostly whole minimally processed foods.
A diet is just a pattern of eating there are so many variables it depends but we should tie in the basic concepts:
There is a lot of conflicting information about nutrition from a lot of non experts.
Obesity is complex and should be treated as such
Weight loss, weight gain, and maintenance happen because of energy balance.
Calories in and calories out is not the same as calorie tracking
There are 3 different macronutrients: protein, carbohydrates, and fats.
Higher protein intake has benefits for weight loss, retention of lean mass, and for athletes.
Carbohydrates are essential for energy in many respects and high intake. of dietary fiber is associated with many health benefits.
When it comes to fats we should consume less saturated fat and more unsaturated fat.
Micronutrients are essential for bodily functioning and development.
Fruits and vegetables are abundant in these micronutrients.
Your specific nutrition needs will depend on many factors there is no perfect diet.
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