Introduction
Obesity management strategies, including caloric restriction, very-low-calorie diets (VLCDs), and meal replacements, often result in moderate short-term weight loss. However, sustaining these results poses a significant challenge for many individuals. Current clinical guidelines underscore the critical role of dietitians in improving patient outcomes through nutritional therapy, emphasizing personalized interventions such as behavioral counseling and physical activity to enhance long-term adherence and success. When combined with pharmacotherapy and bariatric surgery, the focus shifts from mere weight loss to broader health improvements, highlighting the need for a holistic and patient-centered approach.
The Evolving Role of Dietitians in Obesity Management
This article explores the evolving role of dietitians in obesity management, advocating for a shift from a weight-centric approach to a more holistic model that prioritizes overall health gains. Key areas of interest include the impact of dietetic interventions on metabolic health, cardiovascular function, gut microbiome balance, inflammation, and psychological well-being. By focusing on non-scale victories, such as improved insulin sensitivity, lipid profiles, and mental health, dietitians play a crucial role in driving long-term success in obesity management.
Current Nutritional Therapies and Dietetic Interventions
Current nutritional therapies and dietetic interventions for weight management employ various approaches designed to promote sustainable weight loss and long-term maintenance. These approaches generally show modest weight reduction. Most diets tend to achieve 4-10% weight loss within 6-12 months, with more structured and restrictive diets, like meal replacements and very-low-calorie diets (VLCDs), reaching up to 15% weight loss. Sustained success in weight management depends heavily on continuous counselling and behavioral support. Combining nutritional therapy with behavioural interventions, such as cognitive behavioural therapy (CBT) and motivational interviewing, has been shown to improve adherence and facilitate long-term weight maintenance. Studies show that patients who receive ongoing dietitian support are more likely to maintain a 5-10% weight loss over 1-2 years. All these strategies show a higher success rate when the dietetic approach is tailored to the individual’s specific needs and context. Personalised plans contribute to better adherence, which in turn helps with the maintenance of weight loss.
Challenges in Maintaining Long-Term Weight Loss
While dietitians employ various strategies to help patients manage obesity, evidence highlights significant challenges in maintaining long-term weight loss. These challenges include weight regain after 12 months, difficulty in sustaining adherence to dietary plans, and the ongoing need for personalized interventions and support. Prolonged calorie restriction not only risks causing nutrient deficiencies, which can worsen existing health conditions, but also triggers neurobiological changes that promote weight regain by disrupting appetite regulation and increasing cravings, leading to overeating.
An additional challenge to providing sustained nutritional counselling is financial and systemic barriers. Many patients stop counselling not due to a lack of interest but because of limited insurance coverage or financial constraints. Insufficient coverage for extended sessions can hinder long-term follow-up, increasing the risk of weight regain as patients struggle to maintain dietary and behavioral changes. Clarifying patients’ expectations regarding the number of visits and the overall scope of the program before treatment begins can help improve adherence. By setting realistic expectations and planning for the necessary number of follow-up sessions, patients are more likely to commit to the full course of counselling, reducing this issue as a barrier to successful treatment.
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The Pivotal Role of Nutritional Therapy
Nutritional therapy plays a pivotal role in weight management. Guidelines from the EASO, the Association for the Study of Obesity on the Island of Ireland (ASOI), and the Brazilian Association for the Study of Obesity and Metabolic Syndrome (ABESO) all recommend a daily caloric reduction of 500-1000 kcal. While various macronutrient ratios can be effective, patient adherence is critical. A diet that can be sustained over time is more important than a specific macronutrient breakdown. Guidelines from the EASO and the ABESO emphasize the importance of choosing nutrient-dense foods like fruits, vegetables, whole grains, lean proteins, and healthy fats. Minimally processed foods should be prioritised to maintain satiety and improve overall health.
Nutritional Therapy in Conjunction with Pharmacotherapy and Bariatric Surgery
Pharmacotherapy, using medications like glucagon-like peptide-1 (GLP-1) agonists, helps to reduce appetite and increase satiety, making it easier for patients to adhere to reduced-calorie diets. Another type of medication, known as lipase inhibitors, works by blocking gastric and pancreatic lipase, which reduces the amount of fat absorbed from the diet.
Nutritional therapy serves as a foundational component of pharmacotherapy, enhancing patients’ health outcomes beyond weight loss. It supports patients through the following: (a) guiding them toward healthier eating patterns; (b) managing potential gastrointestinal side effects; and (c) preventing nutritional deficiencies. While pharmacotherapy is effective, it does not eliminate the need for dietary changes. Although the medication reduces the pressure on patients to actively lower their calorie intake by naturally curbing appetite, the role of the dietitian becomes even more critical in ensuring the quality of food choices. Dietitians must ensure patients receive adequate nutrition despite a reduced appetite and lower calorie intake. Additionally, they should work closely with the medical team to determine the optimal medication dose, which may not necessarily be the highest, but rather the one where the patient feels their best, consuming a moderate amount of healthy calories while still achieving weight loss or maintenance. Therefore, nutritional guidance remains essential to maximizing the long-term effectiveness of pharmacotherapy in weight management.
Bariatric surgery is the most effective weight loss strategy. However, nutritional intervention is crucial both pre- and post-surgery to ensure successful outcomes and prevent surgical complications. The goals of nutritional therapy in bariatric surgery include the following: (a) guiding the patient to follow a very low-calorie diet to reduce liver size pre-surgery and optimize surgical outcomes; (b) helping the patient develop healthier, sustainable eating habits; (c) supporting post-operative healing through a progressive diet; and (d) preventing malnutrition and ensuring proper supplementation of essential nutrients.
Expanding the Role of Dietitians
The role of dietitians extends far beyond simple weight loss, significantly influencing lifestyle changes, improving the quality of life, and preventing the complications that arise from weight management therapies. However, there remains a notable lack of standardized guidelines on how to approach diverse weight loss strategies and effectively measure improvements in non-weight-related outcomes.
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Shifting from Weight Loss to Health Gain
This article advocates for redefining the dietitian’s role by shifting the focus from primarily achieving a calorie deficit for weight loss to adopting a more holistic approach that prioritizes overall health improvements. While calorie reduction remains a key component of weight management, success in treatment should not be defined by weight loss alone. Instead, standardized evaluation metrics should include other important health outcomes, such as metabolic health, cardiovascular function, mental well-being, and quality of life.
Health Improvements Beyond Weight Loss
Dietetic interventions have been shown to provide significant health improvements beyond weight loss. These include enhanced metabolic and cardiovascular health, better gut microbiome balance, reduced inflammation, improved sleep quality, mental well-being, and overall quality of life.
Metabolic Parameters
Metabolic parameters are one of the most improved elements through dietetic intervention. The Mediterranean diet, rich in monounsaturated fats from olive oil, nuts, and fish, has been shown to reduce LDL cholesterol and improve HDL cholesterol levels, leading to a more favorable lipid profile and reduced cardiovascular risk. The DASH diet, which emphasizes fruits, vegetables, and low-fat dairy products, is particularly effective in reducing blood pressure, likely due to its high potassium and magnesium content, along with its low sodium intake. These improvements in blood pressure contribute directly to better endothelial function, a key marker of cardiovascular health.
In addition to these cardiovascular benefits, dietary interventions also impact metabolic hormones. Contrary to the effect of a prolonged caloric restriction that can lead to disrupted appetite regulation, increased cravings and, ultimately, increased food intake, certain dietetic approaches can aid in improving leptin signalling. Diets with a low glycemic index or those high in protein can help regulate appetite by improving leptin sensitivity and promoting fat loss from visceral adipose tissue, which is often associated with insulin resistance, helping to maintain stable insulin levels thus reducing cravings for high-calorie foods and improving overall metabolic health. By targeting the hormonal dysregulation common in obesity and the cardiovascular risks associated with metabolic syndrome, these dietary strategies can promote sustainable health improvements, lower the risk of metabolic diseases, and improve quality of life.
Gut Microbiome Balance
The trillions of microorganisms that compose the gut microbiome plays a crucial role in regulating digestion, immune function, and energy metabolism. Specific dietary patterns can shift the composition and function of the gut microbiota, leading to improvements in metabolic processes that are independent of weight loss. Dietary interventions that increase fibre intake enhance short-chain fatty acid (SCFA) production, such as acetate, propionate, and butyrate. SCFAs’ influence in gluconeogenesis, promotes improved glucose tolerance and reduced fat accumulation, thereby increasing bile acid metabolism, which is critical for fat digestion, and positively impacting lipid metabolism. These metabolites regulate fat storage and energy expenditure by favouring the growth of beneficial bacteria. Additionally, SCFAs modulate the production of hormones involved in appetite regulation, such as peptide YY (PYY) and GLP-1, which contribute to enhanced satiety and energy balance.
Read also: Weight Loss with Low-FODMAP
Inflammation Reduction
Chronic inflammation, defined as a prolonged, low-grade inflammatory response that persists over time, is characterized by elevated levels of circulating pro-inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Clinically, these biomarkers are often measured to assess the degree of systemic inflammation in humans, particularly in conditions like type 2 diabetes, cardiovascular disease, and metabolic syndrome. High-fibre diets, which increase SCFA production are particularly effective in reducing inflammation through inhibiting the production of pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-α), and promoting the development of regulatory T cells, which are essential for maintaining immune homeostasis.
In addition to fibre, diets rich in omega-3 fatty acids, polyphenols, and other bioactive compounds also play a crucial role in reducing inflammation. Omega-3 fatty acids have been shown to decrease the production of inflammatory eicosanoids and cytokines. Polyphenols, found in fruits, vegetables, and whole grains, exert anti-inflammatory effects by modulating the nuclear factor-kappa B (NF-κB) pathway, which is a critical regulator of inflammatory responses.
Improved Sleep Quality
Obesity-related factors such as chronic inflammation, insulin resistance, and increased appetite-regulating hormones, such as ghrelin, contribute to disrupted sleep patterns, including obstructive sleep apnoea (OSA). These disturbances are exacerbated by poor sleep quality, which itself can promote weight gain through dysregulated appetite control, leading to increased cravings for high-calorie, nutrient-poor foods. Nutritional interventions that promote balanced macronutrient intake, particularly by increasing fibre and lowering glycaemic index, can enhance sleep quality independently of weight reduction. Micronutrients like magnesium, zinc, and melatonin supplements have shown to enhance sleep quality by regulating the sleep-wake cycle and reducing sleep onset latency. Diets that are high in fibre and low in sugar and saturated fats are associated with deeper and more restorative sleep, whereas high-sugar diets result in lighter, less restorative sleep. The Mediterranean diet has been associated with improved sleep quality due to its high content of antioxidants, omega-3 fatty acids, and anti-inflammatory properties.
General Guidelines for a Healthy Diet
A healthy diet comprises a combination of different foods, including staples like cereals (wheat, barley, rye, maize or rice) or starchy tubers or roots (potato, yam, taro or cassava), legumes (lentils and beans), fruit and vegetables, and foods from animal sources (meat, fish, eggs and milk). Breastfeeding fosters healthy growth and may have longer-term health benefits, like reducing the risk of becoming overweight or obese and developing noncommunicable diseases later in life. Feeding babies exclusively with breast milk from birth to 6 months of life is important for a healthy diet. It is also important to introduce a variety of safe and nutritious complementary foods at 6 months of age, while continuing to breastfeed until your child is two years old and beyond.
Vegetables and fruit are important sources of vitamins, minerals, dietary fibre, plant protein and antioxidants. People with diets rich in vegetables and fruit have a significantly lower risk of obesity, heart disease, stroke, diabetes and certain types of cancer. Fats and oils and concentrated sources of energy. Eating too much, particularly the wrong kinds of fat, like saturated and industrially-produced trans-fat, can increase the risk of heart disease and stroke. Using unsaturated vegetable oils (olive, soy, sunflower or corn oil) rather than animal fats or oils high in saturated fats (butter, ghee, lard, coconut and palm oil) will help consume healthier fats. To avoid unhealthy weight gain, consumption of total fat should not exceed 30% of a person's overall energy intake. For a healthy diet, sugars should represent less than 10% of your total energy intake.
The Obesity Pandemic and Research Efforts
Obesity is a pandemic, and one center of the pandemic is the United States, where about 40% of adults and over 20% of adolescents ages 12-19 are obese, according to the Centers for Disease Control and Prevention. The disorder contributes to heart disease, stroke, Type 2 diabetes, certain forms of cancer and many other ailments. The driver for overweight and obesity is simple: regularly consuming more energy than we need to maintain a healthy body weight. However, the underlying biological mechanisms and solutions are far less clear. “We don’t know why somebody can eat one type of diet and be fine, while somebody else eats that same diet and becomes overweight,” says Kimberly Kinzig, associate professor of psychological sciences.
Researchers are pursuing a broad sweep of obesity-related studies across fields ranging from nutrition science and psychology to biology and food science to understand eating behaviors and their results. Investigators seek to understand the mechanisms determining why, when, what and how much people eat and the effects on our health. Eating is a complex activity, especially for omnivores like humans. As Mattes notes, “Every time we eat, we put different chemicals in our mouth, and our body has to determine how to handle them. One focus of his lab is exploring how the sensations involved in appetite are modified both by the properties of food and beverages and by human characteristics such as levels of obesity and physical activity. “The physiological processes involved in food ingestion, digestion and nutrient metabolism are all initiated by the sensory properties of foods,” he says.
Specific Food Effects and Sweeteners
Some striking findings have come from clinical research comparing the effects of consuming liquids versus solids. “Our initial thinking might be: A calorie is a calorie, so the source of energy should be of little consequence,” Mattes says. “But everything about how we handle those two food forms is quite different. On a brighter side, human observational studies have long suggested rather puzzlingly that nuts, a high-fat food, actually may aid people struggling to manage their weight. Clinical trials led by Mattes and others validated that finding from observational studies. They conducted human trials that pointed to three main reasons: Nuts have a satiating effect, the energy from nuts is not efficiently absorbed, and their consistent consumption may raise energy expenditure.
Mattes is shedding light on some previously unexpected actions of low-calorie sweeteners such as aspartame, saccharin, stevia and sucralose. “We talk about these sweeteners as if they’re all the same, but each of these compounds is a unique chemical,” he notes. “Pretty much everything about them (such as sensory properties, digestion, absorption and effects on hormones) is different. The initial findings are that these sweeteners had varied effects on body weight. Susan Swithers, professor of psychological sciences, has demonstrated in rodents that low-calorie sweeteners actually can worsen rather than improve weight problems, because the sweeteners can interfere with the ability to deal with regular sugars. Normally, things that taste sweet are very good predictors to expect an incoming dose of energy, she explains. “But when you introduce an artificial sweetener, your body is learning that sweet taste is no longer a reliable predictor,” Swithers says.
Long-term observational studies repeatedly have found that drinking diet sodas each day is associated with Type 2 diabetes, stroke, hypertension, cardiovascular disease and dementia. “Maybe people who are unhealthy or concerned about their weight choose to consume these sodas, but it could also be the case that these products are making it harder for people to achieve healthy outcomes,” she says. It’s not practical to solve this problem in clinical research, one reason being that even with the best intentions, people simply don’t report their consumption accurately. But Swithers’ work with animal models has helped to clarify what is cause and what is effect. “We don’t have animals that have said, ‘I’m concerned about my weight, I’m going to switch to diet soda,’” she remarks. In one project, Swithers’ lab is following up on human studies that found that babies of mothers who drank diet soda while they were pregnant have an increased risk for overweight and obesity at one year of life. In the meantime, Swithers offers straightforward diet advice: “Reduce the amount of sweeteners you’re consuming, whether they have calories or not.
Gut-Brain Connection and Brain Inflammation
Edward Fox, associate professor of psychological sciences, looks at how the gastrointestinal system sends messages back to the brain to help control feeding behavior. Fox’s work centers primarily on the vagus nerve, the longest nerve in the autonomic nervous system. The vagus nerve is thought to carry most of the messages back from the gastrointestinal tract that tell the brain to stop eating when you’ve had enough. “When you sit down to eat, it largely determines how much you eat,” he says. One project is to examine precisely how the vagus and other nervous systems are embedded throughout the gastrointestinal tract. “All these nerve endings tangled up in the gut are confusing, and it’s hard to decipher what’s going on,” Fox says. “But it’s really important, because that’s where nutrients are absorbed. Fox and his co-workers are finishing up the first map of how nerves are distributed along the length of the small intestine. His other major area of research looks at how satiation signaling from the gut is handled in the area of the brain stem where it enters the brain. “We’re trying to identify the specific cells that are activated by those signals, and to study their connections and how they influence feeding, because we don’t really know what circuits they’re forming in the brain,” Fox says.
Her research in rodents helps to analyze the mechanisms at work. Within one day of being put on such a diet, the animals display inflammation in the brain, Kinzig says. Some of her studies focus on the hippocampus, a region of the brain with many tasks in feeding. In rodents on a Western diet, “inflammation hits the hippocampus hard,” Kinzig says. The response comes in phases: inflammation soars after 10 days, subsides by 40 days, then rises again at 90 days. There’s a surprisingly similar pattern in cognitive tasks involving the hippocampus, Kinzig says. Her lab is now looking at how blood brain barrier damage can contribute to brain inflammation and contribute to cognitive decline. Similarly, work in animals by researchers in the Swithers lab points to risks in this part of the brain. “There is strong evidence that eating a Western diet can produce damage to the hippocampus, which may normally tell you not to eat even when there are cues that tell you that food is available,” Swithers says. “So you eat more, which causes more damage.
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