The Importance of Nutrition for Weight Loss
Achieving and maintaining a healthy weight is a goal for many Americans.
Studies have shown that America's era of significant weight gain began around 1980, most likely caused by significant changes in the American diet (1). The average weight of our population steadily continued to rise for the next 40 years, and it probably comes as no surprise that levels of weight gain surged during the COVID-19 pandemic (2). Indeed, a nationwide population-based study from 2022 found that 48% of us experienced some amount of weight gain during this time and that the greatest predictors for weight gain were levels of psychological distress - from heightened anxiety and depression - and pre-pandemic weight.
A study released by the National Institute of Health (NIH) in 2022 finds that 73.8% of American adults are currently overweight or obese (3). An NIH study from 2021 estimates that 30.7% of children ages 10-17 are overweight or obese (4). While both of these statistics are concerning, this latter statistic is of greatest concern because many overweight and obese children will go on to become overweight and obese adults.
A systematic review and meta-analysis from 2023 found that overweight adults face a 26% increased risk of developing multiple chronic health conditions (5). The same study found that adults with obesity face a 45% increased risk. Chronic health conditions that are often associated with overweight and obesity include high blood pressure, high cholesterol, insulin resistance, metabolic syndrome, type-2 diabetes, cardiovascular disease, chronic liver disease, chronic kidney disease, osteoarthritis, and sleep apnea, among others.
A systematic review and meta-analysis from 2023 found that modest weight loss of 5-10% of total body weight can be clinically meaningful and lead to improvements in blood sugar, blood pressure, body composition, and overall health (6).
In this article, we're going to dive into potential factors that can influence weight gain, we're going to look at different weight loss methods, we're going to learn about the importance of nutrition for weight loss, and we're going to identify strategies that encourage long-term weight maintenance.
Factors that can increase the risk of weight gain
This is typically broken down into non-modifiable and modifiable risk factors.
Non-modifiable risk factors
The most common non-modifiable risk factor is genetics (7). Alterations in genes that control appetite, satiety, metabolism, and body fat distribution can potentially come into play. In overweight and obese individuals, genetics may account for 25% to 70% of their predisposition to carry excess weight. Those with a potentially stronger genetic propensity tend to have been overweight most of their lives (early onset), they tend to have overweight or obese parents or other close blood relatives, and their attempts to lose weight through consistent physical activity and adherence to eating fewer calories over the long term have largely been unsuccessful.
Modifiable risk factors
Eating healthy foods can optimize our genetic expression
While our genetics can be predictors of what we have in store, thankfully they don't always have the last word. While the term "genetics" refers to our DNA which is inherited from our parents and is non-changing, the term "epigenetics" refers to how our genes are expressed, and different influences from the environment can affect this expression (7). Aiming to improve our eating habits by consistently eating healthy whole foods, minimally processed foods, and getting plenty of physical activity can influence our genetic expression in beneficial ways. Lifestyle habits such as getting restorative sleep, reducing stress, cutting down on alcohol, and quitting smoking can all work to enhance our genetic expression as well.
Overall, our eating habits will have the greatest impact on our weight and overall health (7). The Standard American Diet (SAD) is rich in added sugar, sugar-sweetened beverages, refined carbohydrates, saturated fats, and ultra-processed foods (1, 7). Each of these "food groups" contains excess calories and few amounts of vitamins, minerals, fiber, and other beneficial nutrients. Working to limit and even eliminate these items over time can have a profound effect on weight and health.
Besides the prevalence of the SAD diet mentioned above, Americans are generally overwhelmed with an "obesogenic environment" (7). Around every corner, we can find convenient fast food chains, inexpensive meal deals with upsized fries and drinks, and excess marketing campaigns encouraging us to eat cheap processed foods with addictive additives. Also contributing are longer commutes and work hours, sedentary jobs, and excess time behind screens.
Lack of physical activity has been associated with greater risks for overweight and obesity (7). Interestingly, even light exercise has been shown to benefit individuals with a strong genetic propensity for obesity. A study from 2023 estimates that 28% of adults and 81% of adolescents are largely physically inactive.
Different weight loss methods
Calories and food intake
The calorie was identified in the mid-1800s, and as early as 1920, people began to count calories to lose weight. For decades weight loss has revolved around the concept of "calories in, calories out," and this is based upon the model of energy balance (8). Calories from food are required to fuel all of the body's processes - heartbeat, thinking, breathing, digesting, watching TV, mowing the lawn, walking, running, etc., and the relationship between the calories eaten and the calories burned creates an energy balance.
If more calories are eaten than are required to fuel the body, then the excess will be stored for future use. Some of the excess may be stored in the muscles or liver, but the majority is stored in fat tissues throughout the body. From an ancestral perspective, the human body is designed to do this in case there are unexpected periods of reduced food availability. If fewer calories are eaten than are required, then a calorie deficit is created, and this typically leads to weight loss. Being in a calorie deficit encourages the body to turn inward and burn through the excess energy stores that are present. If calorie intake roughly matches the body's energy needs, then weight would be expected to stay the same.
There is a great deal of evidence supporting the energy balance model, however, it takes too simplistic of a view. It suggests that being in a caloric deficit is all that matters and that the types of foods eaten aren't important. With this line of reasoning, it could be expected that eating a diet full of processed foods with few nutrients would work as well for weight loss as having a mostly healthy diet. Research doesn't support this.
Processed foods, hunger, and satiety
When it comes to steady and sustainable weight loss, feelings of hunger and satiety are important variables to consider. Studies in humans have shown that diet plans based mostly on ultra-processed foods with higher amounts of added sugar, sodium, and saturated fat lead to increased biochemical secretion of hormones related to hunger, decreased secretion of hormones related to satiety, and increased food intake (9). Conversely, diet plans that rely on fresh whole foods and include plenty of fiber, lean protein, and healthy fats have been shown biochemically to do just the opposite and help limit hunger and boost satiety. With 60% of the average adult diet and 70% of the average youth diet consisting of processed foods, it becomes abundantly clear that a shift towards a healthy diet plan is crucial if weight loss or weight maintenance are goals (10).
While eating fewer calories and more whole real foods with fiber, lean proteins, and healthy fats appear to be important for weight loss, what is less clear is which dietary patterns and specific healthy foods should be included. Indeed, there are many ways to approach this, and the answer will be unique to each individual.
Different types of "diets"
Going back as far as the 1970s, the United States has been inundated with healthy eating options, and each has enjoyed their day in the sun. Some are intent on restricting or boosting certain macronutrients, such as low-fat or high-fat, high-protein, and lower or higher carbohydrate intake. Others tend to be more balanced but may have some other type of therapeutic focus, such as the Mediterranean diet, Paleo diet, ketogenic diet, Nordic diet, vegetarian and vegan diets, the DASH diet, the MIND diet, Whole 30, the Autoimmune Protocol, gluten- and dairy-free diets, the Mayo Clinic diet, the American Heart Association diet, and the American Diabetes Association diet. To add further to the mix, the US government releases new updated dietary guidelines every five years that may be similar or quite different from any one of the diets listed above. And if that's not enough, knowing what to eat has at times been overshadowed by when to eat, and there is a flood of information on intermittent fasting. Easily one of the most common phrases that certified and licensed nutrition professionals hear from their clients is that they are completely confused, overwhelmed, and intimidated by all the nutrition and dietary information that is out there.
Research informs us that in general, the chosen whole food dietary pattern may be less important than consistently placing the body in a caloric deficit and including satiating whole foods, especially during the weight loss phase. Indeed, a systematic review and meta-analysis from 2020 which compared 14 different popular diets found that most well-constructed dietary patterns showed similar effectiveness in weight loss and improvement in cardiovascular risk factors at six months (11). With this in mind, the "right" healthy eating plan for a specific individual should match their preferences, meet their nutrient requirements, and be founded on whole real foods. This will look different for everyone. I always like to say, "The best eating plan for a client is the one that they will actually follow."
Intuitive eating
Intuitive eating is an approach to weight loss that emphasizes connecting with internal cues for satiety, hunger, and appetite rather than relying on external cues or recommendations, such as eating at exact times of the day or conforming to other cultural norms (12). This approach emphasizes having a positive relationship with the body and food, and it is often effective for individuals experiencing disordered eating. In research, some studies have shown intuitive eating to have varying levels of effectiveness for weight loss, but typically it falls short when compared with interventions that involve eating fewer calories (13). This shortfall usually involves alterations to hunger and satiety hormones that occur when an individual has been overweight or obese long-term (14).
Commercial weight loss programs
Research shows us that programs such as Optavia (Medifast), Jenny Craig, and SOTA can be effective in helping people lose weight (15). These programs typically do not rely on the intake of healthy meals or real food but instead rely on ultra-processed meal replacements, such as shakes, bars, chips, soups, and pre-packaged dried or frozen meals.
These programs are effective over the short term because they directly control serving sizes and portions, they reduce the need for meal planning and cooking, and they reduce energy intake and place you into a caloric deficit. These programs typically are not effective over the long term because they are expensive, they do not rely on whole real foods that are full of nutrients, they may contain high levels of sodium, they may cause dizziness and headache due to calories being too low, and they can cause constipation and other gastrointestinal complaints due to lack of fiber in their products.
A huge concern about these programs is that most do nothing to educate their clients on transitioning over to a balanced diet filled with whole real foods once their weight loss goals are met. They typically don't teach about proper portion sizes based on real foods, and they typically don't teach their clients how to meal plan or cook. Commonly, once individuals reach their desired weight on these programs, they discontinue the program and go back to their pre-program eating habits, regaining most of the weight that they lost. This leads to a vicious cycle of program re-entry to lose weight again, and it leaves individuals dependent on their services and products.
Weight loss drugs
Weight loss drugs, such as those in the GLP-1 agonist family (i.e., Ozempic, Wegovy, Mounjaro) have recently soared in popularity around the world. They have been shown in research to be effective in improving type-2 diabetes, weight, and cardiovascular risk factors (16). These weight loss drugs are effective because they stimulate greater secretion of insulin, and they suppress appetite by slowing down the emptying of food in the stomach and by limiting the production of an important hormone that increases hunger. In terms of weight loss in those who are overweight or obese, weight loss outcomes can range from 5-15% of total body weight. This can be impressive, and countless studies have shown that as weight decreases, the risk for chronic disease decreases as well.
These drugs can be an effective choice for those who have treatment-resistant type-2 diabetes or for those who are significantly overweight or obese and have been unable to lose appreciable weight through consistent dietary and lifestyle efforts. There is evidence from clinical trials that once these drugs are started for weight loss, individuals may need to remain on them long-term to maintain weight. A study from 2022 found that those who were overweight or obese and lost 17.3% of their weight on semaglutide (Ozempic, Wegovy) regained 67% of their lost weight within one year after discontinuing the drug (17).
Gastrointestinal side effects, such as nausea, vomiting, bloating, diarrhea, and constipation are common, and these drugs can raise the risks for pancreatitis, pancreatic cancer, gallbladder events, thyroid cancer, acute kidney injury, gastroparesis (stomach paralysis), and intestinal blockage (18). These risks are rare, but as more individuals use these drugs, the incidence of these conditions is expected to rise.
Due to these drugs' ability to significantly reduce appetite and food intake, it is extremely important to ensure that the foods being eaten are full of nutrients to prevent malnutrition. Additionally, due to the potential risk of weight regain once these drugs are discontinued, it would be wise for individuals considering stopping the drugs to meet with a certified nutrition professional beforehand so that new dietary and lifestyle habits may be established and lost weight may be maintained.
Eating whole real foods
We have already touched on the fact that there are many different dietary patterns and that each of us may have specific preferences and needs. However, in general, the most effective eating habits for losing weight may include many of the following healthy unprocessed foods: lots of fresh vegetables and fruits, various plant-based proteins, whole grains rather than those that are refined, lean meats, fatty fish, and healthy fats, such as olive oil. Minimally processed items, such as low-fat dairy foods may be included as well, if tolerated.
Physical activity
Regular physical activity has not only been shown to help with losing weight and weight management, but it also supports optimal health in a multitude of other ways (19). Regular exercise benefits the heart, arteries, veins, bones, muscles, tendons, ligaments, lungs, brain, mitochondria, breasts, testes, pancreas, liver, and gut, and it can lead to improvements in muscle mass, metabolism, body fat distribution, overall body composition, blood flow, cognition, mood, energy levels, movement, balance, sexual health, hormone balance, immunity, aging, and longevity. It is estimated that regular physical activity can delay the onset of approximately 40 different chronic diseases.
Rapid versus gradual weight loss
Oftentimes when individuals decide they are ready to lose weight, they want it to happen NOW. I always remind them that they didn't reach their current weight overnight and that they typically can't expect it to improve overnight.
Research has explored gradual versus rapid weight loss in humans, and it has been shown that while the amount of weight lost may not differ significantly over time, gradual weight loss results in greater reductions in fat mass and body fat percentage, and it preserves metabolism to a greater extent (20). Rapid weight loss typically results in greater loss of lean mass.
Long-term weight management
Periodic follow-ups with a certified nutrition professional can help provide support and accountability
We all have either personally experienced or observed in others that consistent weight loss efforts result in lost weight. We feel great and we keep going. Then we hit a plateau and our weight loss begins to slow, whether or not we have reached our target weight. We become discouraged and may even give up on our efforts. The weight begins to creep back on and we gain most of our lost weight back. Sound familiar? This was my reality for many years.
During the weight loss phase, alterations in hunger and satiety hormones and increased appetite can lead to intake of larger portions and weight regain, especially when a discouraging weight loss plateau is experienced (21). Some of the signaling of these hunger and satiety hormones may even be happening below the level of consciousness. Additionally, a slowing metabolism may result in fewer calories being burned given the same amount of regular physical activity. Further, genetics and insulin resistance can play their parts.
Research has shown that sustainable weight loss over the long term relies on several different factors, which can include
adopting a balanced dietary pattern that is mostly centered around whole real foods
having a greater reliance on foods that increase feelings of satiety
being mindful of portion sizes that are appropriate for personal long-term goals
regularly incorporating physical activity
engaging in frequent meal planning, or learning how to do so
engaging in frequent cooking, or learning how to do so if confidence is low
identifying personal thresholds that signal the need to reengage in weight management efforts
refocusing and not giving up if there is a lapse in efforts
scheduling check-ins with a certified nutritionist for increased support and accountability, especially during the first year
ensuring that the goals that have been set are realistic
rediscovering the "why" and the initial motivation(s) that started the weight loss journey
focusing on how much has been accomplished rather than on what has not yet been achieved
As you can see, many factors go into weight loss, weight management, and optimal health. Contact us today and we can assist you in starting your weight loss journey and support you as you set and reach your goals!
References
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