Nutrition Science and Everyday Application - beta v 0.1

380 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
is digested and how well the macronutrients are absorbed—factors which vary depending
on the food itself, the digestion efficiency of the person eating it, and even the microbes
living in their gut. Two people may eat the exact same meal, yet not absorb the same number
of calories.
Energy expenditure is also dynamic and changes under different conditions, including
increased or decreased caloric intake. Decreased caloric intake and going into negative
energy balance cause a drop in BMR to conserve energy. Muscles also become more
efficient, requiring less energy to work, and without realizing it, people in negative energy
balance often decrease their NEAT activity level. These adaptations help to conserve body
weight and make it more difficult to stay in negative energy balance. People may still be able
to lose weight despite their bodies working to prevent it, but maintaining a new, lower weight
requires constant vigilance, and weight regain is common.
Research has also shown that people respond differently to positive energy balance. When
a group of people are overfed, the amount of weight gained amongst study participants
varies widely. In a study of identical twins who were given an extra 1,000 calories per day
for 100 days, weight gain varied between 10 and 30 pounds among participants. Weight gain
between twins was more similar (though not exactly the same), which may be attributed
to genetic factors. 6 People gain and lose weight differently; we don’t necessarily follow
formulas.
When people say that the answer to the obesity epidemic is to eat less and move more,
they’re not wrong. But this is also an oversimplified answer, because of all the complexities
underlying energy intake and energy expenditure.
Self-Check
An interactive H5P element has been excluded from this version of the text. You can view it online here:
https://openoregon.pressbooks.pub/nutritionscience/?p=589#h5p-20
References:
• “Balancing Energy Input with Energy Output”, section 11.2 from the book An
Introduction to Nutrition (v. 1.0), CC BY-NC-SA 3.0
• 1 Chun, N., Park, M., Kim, J., Park, H., Hwang, H., Lee, C., Han, J., So, J., Park, J., & Lim,
K. (2018). Non-exercise activity thermogenesis (NEAT): a component of total daily