Thursday, 28 October, 2021
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Why Your Diets Don't Work



why-your-diets-dont-work

Annusuya Ghimire

The World Obesity Federation outlines the prevalence of obesity to have nearly tripled between 1975 and 2016. Similarly, WHO reports show 13% of the total adult population falls under the obese category.
A 2013 survey in Nepal also shows how 17.7% of the Nepali population aged 15-69 become obese. While Nepal has been battling with issues regarding malnourishment in its population, obesity poses another big problem as statistics show obesity to kill a larger number of people than those who are underweight in contemporary society.

Over Consumption
With overconsumption of food and low expenditure of energy resulting in the accumulation of fat cells being highlighted as the main cause behind obesity, numerous diets with a focus on specific macronutrients and lifestyle choices have gained popularity in recent years. Dieting, a systematic reduction of calorie intake has been the most common approach in attempts to reduce weight loss in overweight and obese individuals.
However, upon observing the public, we see most people being engaged in short-term fad diets, which do more harm than good. Each year, about 45% of the world population is engaged in weight loss programmes like Slim Fast, Nutrisystem, Keto and Paleo diet, having the diet industry grow into a 71-billion-dollar industry in the U.S. itself. The irony of these seemingly minutely designed and well-tailored diets and weight-loss programs is that 95% of the diets fail and the diet industry has profited off the pandemic of obesity that so many people are suffering from.

The diet industry preys on the insecurities and poor life choices of individuals while marketing their products through an appeal to authority and using famous authors to sell their products. The majority of diet products focus on the nuances of restricting a particular macronutrient group for weight loss when in reality, the science of weight loss is more complicated, and the results are mostly inconclusive when applied to a larger population.
The majority of diets fail to produce a lasting weight loss. This can be observed looking at a real-life example of the participants in the reality show "The biggest loser" where the 14 participants lost an average of 58 kg during the span of the show but later regained 41 kg on average, as shown by a follow-up study done in 2016. In fact, their resting metabolic rate was 704 calories lower than where they had started, making their energy expenditure rate even slower than what it was initially and thus making it harder to lose weight in the long term and maintain it.

This was further supported by another review comprising of 21 papers and 60,000 participants, which showed that dieters gain everything but 0.9 grams of weight that they lost, all in 2 years after the diet. The reason why weight-loss maintenance is so hard in individuals who achieve it through calorie restriction can be because as a result of the hormones leptin, ghrelin and cortisol.
Leptin is released by the fat cells adipocytes which suppresses appetite by signalling satiety to the brain. In people who restrict their calories and have currently undergone a diet to lose weight, levels of leptin have been found to reduce significantly.

Reduced levels of leptin along with reduced sensitivity to leptin, as seen in obese individuals, results in an inability to detect satiety despite high energy stores and high levels of leptin, which results in overeating to reach the level of satisfaction and alleviate hunger. This can play out in a way that prevents individuals from losing weight and maintaining it for the long-term as someone who feels like they are constantly hungry will eat more and inevitably gain weight.
The level of Ghrelin is also affected when someone undergoes calorie burn. Ghrelin is a "hunger hormone" which signals the need for food intake. In other words, leptin and ghrelin work complementary to each other, where ghrelin sends cues for hunger and leptin sends cues for satiety once food has been consumed.

Thus, ghrelin has the same effect as leptin when it falls as lower levels of leptin result in the feeling of hunger. Individuals who have gone through a calorie-restrictive diet have higher levels of ghrelin, leaving them with a higher appetite. Even a year after undergoing a calorie-restrictive diet, the levels of leptin and ghrelin do not go back to normal, making these individuals susceptible to overeating.
Cortisol, also known as the stress hormone, is another hormone that plays a role in appetite and food consumption. An experiment on mice showed that mice, who underwent a calorie-restrictive diet had a higher level of cortisol. While these mice had a higher level of cortisol during weight loss, they were still found to be very sensitive to stress with their cortisol levels still high, in comparison to mice that had never gone through a diet. It was also noticed that the mice with higher cortisol levels who were under a calorie-restrictive diet tended to binge eat.

The elevated levels of these hormones could help explain why dieters report feeling anxious around food in the aftermath of a restrictive diet. This could be because the stressful experience of being calorie deficient made the mice crave the psychological reward they got upon eating, which caused them to binge.

Calorie Restrictive Diet
Going on a calorie-restrictive diet also has numerous psychological responses. There is a lot of biological and psychological phenomenon put in place which will make us think about food and want to eat. A study showed that individuals who had been calorie deprived had biased attention with a focus on food-related cues.

People’s attention is biased towards food when they have been calorie deprived. This can be seen through eye-tracking studies, dot-probe tasks and neuroimaging studies which have shown that the brain of an individual who is calorie deprived has heightened levels of reward system when it comes to intake, anticipated intake and even images of food.
Individuals who have been under calorie restriction have a much higher sense of smell that makes it harder to resist the food. Individuals who have undergone a 24 hour fast have heightened rewards from food and food-related cues, which causes them to be more distracted by food, in the anticipation for the brain to receive the reward upon eating.
Dieters and individuals who have been calorie deprived also have a preoccupation with thoughts of food. And it is perhaps because of these predispositions and preoccupations that the dieters cannot resist these biological and psychological responses to food once motivation runs out and hence, go on a binge.

Since there is so much misinformation going around about diet and weight loss, it becomes important that we are well-informed about nutrition and health. In fact, not restricting calories and making informed choices about the foods we eat might be a better path to weight loss, as demonstrated by a Stanford study which showed that simply by taking classes on food nutrition and making informed choices, participants made an average of 6 kg weight loss in a year.

It is not the fault of the individual that they do not lose weight or cannot stick to a strict restrictive diet- our body’s mechanisms are working so that we maintain the weight we initially were at to protect us from starvation and maintain homeostasis. Our bodies have come up with a series of processes, which have been perfected throughout evolution to make us fit for survival.
Diets designed by the industry are very calorie-restrictive and lacking in macronutrients which makes one even more prone to binge eating and gaining even more weight.
What we can do is remain informed on the nutritional value of the food we consume and make healthy lifestyle choices so that we can build a healthier body.

(The writer is pursuing studies at Webster University, Thailand)