Increased Hunger May Be the Reason Why Diets Fail
By James J. Kenney, PhD, FACN
Dr. Kevin Hall conducted a study of 14 participants in the "The Biggest Loser" TV show. This study was widely interpreted as showing that the main reason people who lose a lot of weight have trouble keeping it off is that they experience a large drop in metabolic rate. This reviewer was rather critical of Dr. Hall's "Biggest Loser" study and especially the media's take on its implications here:
Although to be fair to Dr. Hall, he did note: "Contrary to expectations, the degree of metabolic adaptation at the end of the competition was not associated with weight regain." The main reason that people on calorie-restricted diets appear to have difficulty losing weight and keeping it off seems to have little to do with abnormally-low metabolic rates but rather gross under-reporting of calorie intake
If a slower metabolic rate was responsible for weight loss plateaus and the cause of weight regain, then Dr. Hall would have found a significant correlation between slowed metabolic rate and weight regain. He did not, and so it was nice to see Dr. Hall setting the record straight in his most recent study.
Dr. Hall's latest study now makes it clear that prior research (including his own) was incorrect. Past research and clinical observations of people not losing or even regaining lost weight on reportedly very low calorie intakes have contributed to the widespread belief that a slowed metabolism was the primary reason people hit weight loss plateaus and have trouble keeping off lost pounds.
New Research Points to a Cause
In his new article, Dr. Hall states: "This [prior research] has led to speculation that the 6- to 8-month weight plateau may be due entirely to the slowing of metabolic rate rather than loss of diet adherence. Our [new] results suggest otherwise and further illustrate that self-reported energy measurements are quantitatively unreliable."
He concludes: "While energy expenditure adaptations have often been considered the main reason for slowing weight loss and subsequent regain, feedback control of energy intake [via increased hunger/appetite levels] plays an even larger role and helps explain why long-term maintenance of reduced body weight is so difficult."
Increased Hunger, Not Slowed Metabolism, is the Main Reason Why Diets Fail
Understanding this is important because focusing on ways to boost metabolism via drugs, supplements, and/or exercise are ignoring the main reason that calorie-restricted diets fail. So why has weight control failure ignored the primary role of increased appetite and focused instead on the far less important role of a slowed metabolic rate?
Research conducted by Dr. Eric Stice and others has shown that portion-controlled calorie-restricted diets not only increase appetite but also greatly increase the desire to eat more calorie-dense foods that are high in fat and/or sugar.
Pitting a powerful biological drive such as hunger against one's intellectual will is in fact likely counterproductive for long-term weight control and may very well be a formula for frustration and disordered thinking about food along with sometimes distorted views of the body itself.
A Trigger for Eating Disorders
Growing evidence suggests that eating disorders arise because of this conflict. Picture trying to limit urine output by measuring it and then stopping at some preordained "correct" amount that is well below what your body tells you to do. How long would your intellectual will to urinate less be able to override the powerful biological urge to urinate?
Yes this strategy still requires some willpower, but in this case it is pitted against cravings for unhealthful fattening foods rather than against the powerful biological drive of hunger.
Focus on WHAT You Eat Rather than HOW MUCH You Eat
As Dr. Stice and colleagues have shown, the increased hunger seen with traditional calorie-restricted diet and exercise programs greatly heightened his subject’s desire to consume highly-palatable calorie-dense foods. This made calorie-dense low-satiety-per-calorie (or fattening) foods far more difficult to avoid over the long term
A more rational approach to reducing calorie intake without increasing hunger is to simply focus change on WHAT you eat. By changing WHAT is consumed to a diet composed largely of minimally-processed plant foods, people will consume far fewer calories without any need to use their intellectual willpower to eat less than hunger demands.
Such a diet would include vegetables, beans, whole grains, and fruit with a low to modest calorie density and high satiety/kcal. Indeed, Dr. Stice's research shows portion-controlled diets actually greatly increase the desire to eat low satiety/kcal foods.
Dr. Stubbs showed that healthy subjects consumed nearly 1500kcal more per day on average over two weeks when consuming the most calorie-dense diet than when consuming the least calorie-dense diet
Calories from Beverages
Also needed for weight control without hunger would be cutting out most beverage calories as these too have been shown to provide less satiety per calorie.
Eating Only When Hungry
Finally, eating only when hungry and until comfortably full (not stuffed) is generally a good approach. Following those simple guidelines is a safer and more effective way to lose excessive body fat stores and improve one's health than by trying to fight hunger while eating low satiety/calorie foods and drinks.
There's a big difference between fighting both hunger and cravings versus cravings alone, which are typically far greater when people are hungrier. Plus, research has shown that cravings for drugs or fattening foods weaken over time and so less and less willpower is required to make healthful food choices.
Increased Hunger Linked to More Calorie-Dense Food Choices
A study conducted by Brian Wansink, Ph.D., and Aner Tal, Ph.D., of Cornell University, Ithaca, N.Y., suggested that hungry grocery shoppers tend to buy more calorie-dense products than shoppers who are not hungry. The research included a laboratory study in which 68 paid participants were asked to avoid eating five hours prior to the study, although during some of the sessions some of the participants were given crackers so they would no longer feel hungry.
A follow-up field study tracked the purchases of 82 participants at different times of the day when they were most likely to be full or hungry. According to the results, hungry laboratory participants chose a higher number of higher-calorie products, but there were no differences between conditions in the number of lower-calorie choices and the total number of food items selected.
Field study shoppers who completed the study at times when they were more likely to be hungry (between 4-7 p.m.) bought fewer foods that were lower in calorie density and more calorie-dense food options compared with those who went food shopping when they were less likely to be hungry.
This shows that even short-term food deprivation and increased appetite can shift food choices so that people choose fewer low-calorie foods, and relatively more high-calorie (and so low satiety/kcal) food options. "The implications of this imaging study are crystal clear; if people want to lose excess weight, it would be more effective to consume healthy, low-fat/low-sugar foods during regular meals, rather than go for long periods of time without any caloric intake." explains Dr. Stice.
Increased Hunger Linked to More Calorie-Dense Food Choices
The time has come to abandon the failed weight control paradigms of the past, which are based on erroneous assumptions about calorie counting and attempts to boost a slowed metabolism. Once you accept that diet and exercise programs fail largely because people get hungry, the primary target for the solution becomes clear.
This information is for educational purposes only. The statements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease. Consult your physician if you have any question regarding a medical condition
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