Nutrition Science and Everyday Application - beta v 0.1

ENERGY BALANCE: ENERGY IN, ENERGY OUT—YET NOT AS SIMPLE AS IT SEEMS 377
contributes anywhere from 15 to 30 percent of energy expenditure and can be further
divided into two parts:
• exercise-related activity thermogenesis (EAT)
• non-exercise activity thermogenesis (NEAT)
EAT is planned, structured, and repetitive physical activity with the objective of improving
health (participating in a sport like soccer or strength training at the gym, for example).
NEAT is the energy expenditure for unstructured and unplanned activities. This includes
daily-living activities like cleaning the house, yard work, shopping, and occupational activities.
NEAT also includes the energy required to maintain posture and spontaneous movements
such as fidgeting and pacing. 1
NEAT can vary by up to 2,000 calories a day for two people of similar size, according to
Dr. James Levine, the Mayo Clinic researcher who first coined the term. NEAT may be an
important component of obesity, and is currently an area of research.
FACTORS AFFECTING ENERGY INTAKE
Given the importance of energy’s role in sustaining life, it’s not surprising that energy
balance is tightly regulated by complex physiological processes. The brain (specifically the
hypothalamus) is the main control center for hunger and satiety. There is a constant
dialogue between our brains and gastrointestinal tracts through hormonal and neural
signals, which determine if we feel hungry or full. Nutrients themselves also play a role in
influencing food intake, because the hypothalamus senses nutrient levels in the blood. When
nutrient levels are low, the hunger center is stimulated. Conversely, when nutrient levels are
high, the satiety center is stimulated.