The 15th Annual Postgraduate Nutrition Symposium, entitled Advances and Targets in Energy Balance and Obesity, took place on July 9-10, 2014.
This annual conference was presented by the Harvard Medical School Division of Nutrition and Nutrition Obesity Research Center at Harvard, Boston Nutrition Obesity Research Center, and the Harvard School of Public Health, Division of Nutrition.
In the meantime, here are some intriguing details from this year’s conference:
David Ludwig, MD, PhD discussed the important question and possible explanations for why the set point at a population level has increased over the years. He discussed the typical energy in/energy out balance explanation (and the touted solution that people should exercise more and eat less), but also raised the possibility that the association between eating more and moving less might instead be a result of metabolic effects of diet. He noted that higher insulin levels from a higher glycemic diet could raise insulin, which promotes anabolic adipose changes (promotion of fat storage), which decreases concentrations of fuel in the blood (glucose, lipids, etc). Per this hypothesis, the result of fewer nutrients available in circulation in the blood stream then causes increased hunger and food intake, and diminished energy expenditure.
Another researcher, Dr. Steven Grinspoon, talked about the potential strategy to treat obesity by targeting visceral adipose tissue specifically, rather than fat overall. Visceral fat, rather than subcutaneous fat, is responsible for the morbidity and mortality associated with obesity. At this time, there are no approved treatments for the specific reduction of visceral fat, but his team is working on using growth hormone-related compounds to potentially do so.
Dr. Aaron Cypess discussed brown fat and its active role in energy expenditure. One interesting aspect of his discussion was that cold temperatures lead to increased energy expenditure by affects on brown fat, or brown adipose tissue (BAT, vs. white adipose tissue).
Dr. John Foreyt addressed behavioral modification and weight loss. One very crucial component of successful weight loss is self-awareness, as pertains to food intake and exercise. However, he explained, it is not about the accuracy of reporting. He stated that people will lie and overstate exercise, and under-estimate food intake. It is the act of engagement in the self awareness exercises of journaling that is pivotal to success. In one study, he and colleagues found that logging of food leading up until study participation predicted future weight loss success – not what was recorded in nutritional or caloric value, but the number of words written, showing that effort to do the logging seemed to make the most difference.
Eve Van Cauter, PhD discussed the effect of sleep on energy balance. Too little sleep leads individuals to eat more frequently, eating more snacks, and leads to wanting higher calorie foods. She presented data showing that those in a sleep deficit eat about 300 cals more food per day than those with adequate sleep. Staying awake more hours does not lead to substantially increased calorie expenditure. Dieting in the context of sleep deprivation leads to similar weight loss as in the adequate sleep group, but the weight loss represents less fat loss. In the long term cohort study of nurses, those who sleep fewer hours per night gained more weight over a 15-year period than peers who sleep adequate hours.
Stay tuned for next year’s topic, Diet and Microbiota in Health and Disease.
Marlene Freeman, MD