Calorie count model is passe. Obesity is about what you eat, not how much

A healthy diet consists of high-quality foods | Representative image | Wikimedia Commons

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aAccording to the World Health Organization, obesity kills at least 2.8 million people globally each year. A sample size of 34,648 people analyzed by the Global Obesity Observatory found that the prevalence of obesity among adults in India was 18.7 percent in the year 2019-20.

This disease is known to be a major risk factor for type 2 diabetes and certain types of cancers, heart disease, stroke, and other diet-related non-communicable diseases. Recently, the US Centers for Disease Control and Prevention reported that obesity may triple the risk of hospitalization due to Covid-19, because weight gain is linked to a weakened immune system. In the United States, between the start of the pandemic and November 18, 2020, there were more than 9,00,000 adults hospitalized with Covid, 30 percent of whom were obese, according to the Journal of the American Heart Association.

But what causes obesity? Is calculating calories the best way to address them?

Expose old models

Research has revealed that losing even a small amount of body weight can significantly reduce the risk of multiple health risks. The world’s population is striving to achieve sustainable weight loss by adopting appropriate lifestyle modifications that include the traditional approach of “eat less, spend more”. However, the “calorie in and calories out” or energy balance model (EBM) has recently been challenged to explain causation and management of obesity through an alternative model presented by Dr. David Ludwig, professor at Harvard Medical School, in the form of the “carbohydrate-insulin” model. (CIM). The latter proposes a bold hypothesis negating EBM and claims that the current obesity epidemic is caused by high consumption of high glycemic index (GL) diets, especially refined carbohydrates found in highly processed and easily digestible carbohydrates such as white sugar and refined wheat. And flour, cake, pastries or chips.

In the research paper, Dr. Ludwig and colleagues argued that EBM does not explain the biological causes of weight gain. This debate presents two major challenges to the nutritional science community – finding the rationale behind the carbohydrate-insulin hypothesis backed by sound scientific evidence, and the credibility of traditional energy balance models in achieving sustainable weight loss.


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The Carbohydrate Model – Insulin Makes It Better

The insulin-carbohydrate model asserts that changes in food quality lead to weight gain. In other words, hormonal and metabolic changes occur due to the body’s response to what we eat rather than how much we eat. The model explains obesity by the interaction of insulin and glucagon in response to foods high in GL. The secretion of insulin increases and the secretion of glucagon decreases when we consume such foods. High insulin levels signal the fat cells to store more calories, leaving a small number available to nourish the tissues. This phenomenon makes the brain think that the body is not getting enough fuel to function, which in turn leads to starvation. CIM advocates manage obesity by understanding the hormonal response and metabolic changes in response to the nature of food and not just its calorie content. However, the EBM fails to record the compositional discrimination of different foods and focuses on caloric values ​​alone.


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A calorie deficit is needed to lose weight

From a biological perspective, weight loss requires a calorie deficit. There is no getting around it. Excess calories from foods are stored either in muscle as glycogen as fat in adipose tissue. Constantly consuming excess calories and not making use of them leads to weight gain, even if we eat the healthiest foods out there on the planet.

Calories ‘in’ – Calories ingested by foods are self-explanatory. Calories out are a combination of resting energy expenditure (REE) defined as the energy required for the body’s basic metabolism at rest, physical activity, and the thermic effect of food (TEF) or diet-induced thermogenesis.

Studies have consistently reported that a calorie deficit caused weight loss, regardless of the source. In a comprehensive 2017 review, Scott Hoyle and Richard Koons cited two highly rigorous studies in the section on metabolism and concluded that these studies failed to support the CIM hypothesis, which predicted that lowering dietary carbohydrates (CHO) should significantly reduce insulin levels, and thus lead to Fats. of adipocytes which ultimately leads to rapid fat loss.

An Endocrine Society scientific statement argued that calorie intake rather than changes in energy expenditure or the internal metabolic environment is largely responsible for the effect of diet on obesity risk. Calories are calories, regardless of their macronutrient content, so habitual consumption of energy-dense palatable diets exposes one to excessive weight gain. In a 2021 review, Yves Schutz and colleagues report that low-carb, ketogenic diets are more “academic” than practical, because these diets are nutritionally unbalanced and cause serious long-term health risks.


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Health is more than just a discussion about calories

EBM is important for weight loss. However, not all calories have a similar effect on hormones and metabolism. For example, two simple sugars, glucose and fructose, provide the same number of calories per gram, but are metabolized through two different pathways. Diets high in fructose lead to insulin resistance and elevated triglyceride levels. Satiety, hunger, and fullness also vary depending on the type of nutrients. Protein and fiber have been found to be more filling than simple carbohydrates. The “calories for calories” theory fails to take nutrient density into account, and therefore lacks credibility in promoting good health in general.

Nutrition must be complete and sustainable

Good nutrition goes beyond weight loss and theory. A varied diet is rich in nutrients and rich in vitamins, minerals and antioxidants that ensure multiple health benefits. There can be N number of theories and models attempting to explain obesity and therapeutic approaches to weight loss, but individuality, local availability of foods, food preference, food intolerances, assessment of medical-physiological conditions, and sustainability are key factors for planning and practical diet prescription. Low-carb diets are well-established nutritional treatments for controlling weight or blood sugar levels. However, the highly reduced forms of these diets give mixed results in determining good health outcomes and compliance. It is also casually marketed as a quick weight loss solution and as such it needs rigorous monitoring and a scientific approach at all times.

Dr. Subhasree Ray is a PhD researcher (ketogenic diet), certified diabetes educator, and clinical and public health nutrition expert. She tweets @DrSubhasree. Opinions are personal.

(Editing Hamra La’iq)

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