Positive energy balance, as reflected by increasing BMI, is not a recent phenomenon. BMI has been increasing for at least 150 years (1), but until the mid to late 1970s, it was associated with improved health and increased longevity. The latter was due as much to advancements in sanitation, the discovery of antibiotics, and administration of vaccinations as better diet quality. However, in the past few decades, the risk-to-benefit ratio has shifted such that the continued increase in body fatness is now implicated with a variety of chronic diseases and the prospect for a slowing or even reversal of gains made in life expectancy. This shifting view has prompted a heightened interest in the controls of energy balance.
Using a familiar analogy, the research strategy to address this problem has resembled a common approach to assembling jigsaw puzzles. As an initial step, the range of pieces is identified and segregated into groups with common properties (e.g., pieces of similar color or geometric shape such as straight edges). Next, fits between pieces within the groups are tested leading to relatively complete clusters. Ultimately, the clusters are linked with transitional pieces resulting in completion of the picture. So, what is the status of the picture of energy balance? A considerable amount of work is still underway to identify the component elements, such as the compliment of gastrointestinal satiety hormones or predisposing personality traits. Social, cognitive, sensory, metabolic, and neural groupings have clearly emerged and are foci of research activity. The result is the growth of clusters, but none are presently, nor may ever be, well enough developed to provide a large enough proportion of the picture to allow meaningful predictions of energy balance in individuals or the population
Although puzzle solving is often a unitary effort where the steps are performed in series, and it is clear who will be responsible for ultimate completion of the effort, research on energy balance is conducted in parallel. This expedites the process in some respects, multiple clusters grow concurrently, but it also presents a problem in that there is less expectation that workers in any one cluster will be responsible for integration of all of the clusters. To advance this process, a workshop was held with the title, “Dietary Synergies in Appetite Control.” The goal was to explore interactions and, more specifically, potential synergies between clusters to better link them. The focus was on appetite because the sensations that define this system reflect contributions from all known clusters, and appetite is widely believed to link energy input and expenditure. To add focus to the discussion, participants were selectively invited to ensure the presence of expertise in processes governing the selection, ingestion, digestion, absorption, and use of foods and the nutrients they contain. The workshop opened with a presentation by David Alison describing the scope and implications of overweight and obesity. This was followed by short updates on knowledge related to the neural (John Blundell), orosesensory (Rick Mattes), gastric/upper intestine (Gerald Smith), and lower intestine/postabsorptive (Stephen Woods) influences on appetite. Next, the approaches and orientation of the food industry to this issue were reviewed (David Mela). Discussion of integration and synergies filled the afternoon, and the workshop was concluded with a summation from the perspective of a clinician (Gary Foster). The latter was viewed as critical for addressing another issue in the field. Although basic scientists recognize knowledge is not complete and are understandably hesitant to make recommendations, public health workers emphasize that the obesity problem is critical and requires remedial action based on current knowledge. A common ground is needed to set sound policy.