A lifetime of change: Measurements of total and basal energy in a large cohort of subjects at ages spanning from before birth to old age document distinct changes that occur during a human lifetime. Pontzer et al . report that energy expenditure (adjusted for weight) in neonates was like that of adults but increased substantially in the first year of life (see the Perspective by Rhoads and Anderson). It then gradually declined until young individuals reached adult characteristics, which were maintained from age 20 to 60 years. Older individuals showed reduced energy expenditure. Tissue metabolism thus appears not to be constant but rather to undergo transitions at critical junctures. —LBR

The aim of the present study was to report the first reliability and validity tests of the remote food photography method (RFPM), which consists of camera-enabled cell phones with data transfer capability. Participants take and transmit photographs of food selection and plate waste to researchers/clinicians for analysis. Following two pilot studies, adult participants (n52; BMI 20–35 kg/m²inclusive) were randomly assigned to the dine-in or take-out group. Energy intake (EI) was measured for 3 d. The dine-in group ate lunch and dinner in the laboratory. The take-out group ate lunch in the laboratory and dinner in free-living conditions (participants received a cooler with pre-weighed food that they returned the following morning). EI was measured with the RFPM and by directly weighing foods. The RFPM was tested in laboratory and free-living conditions. Reliability was tested over 3 d and validity was tested by comparing directly weighed EI to EI estimated with the RFPM using Bland–Altman analysis. The RFPM produced reliable EI estimates over 3 d in laboratory (r0·62;P < 0·0001) and free-living (r0·68;P < 0·0001) conditions. Weighed EI correlated highly with EI estimated with the RFPM in laboratory and free-living conditions (r>0·93;P < 0·0001). In two laboratory-based validity tests, the RFPM underestimated EI by − 4·7 % (P = 0·046) and − 5·5 % (P = 0·076). In free-living conditions, the RFPM underestimated EI by − 6·6 % (P = 0·017). Bias did not differ by body weight or age. The RFPM is a promising new method for accurately measuring the EI of free-living individuals. Error associated with the method is small compared with self-report methods.

A sedentary lifestyle is a risk factor for many chronic conditions, including diabetes mellitus, heart disease, stroke, and certain types of cancers.^1-6 Regular physical activity and higher levels of cardiorespiratory fitness are associated with lower risk for premature mortality, and exercise training has been demonstrated to improve a number of important risk factors, such as cardiorespiratory fitness,⁷ weight, high-density lipoprotein cholesterol level, and fasting insulin level.⁸ Although mood, level of functioning, energy level, and other measures of quality of life (QOL) are purported to be improved by regular exercise, this claim is largely unsubstantiated in populations without significant morbidities. There is strong evidence that regular exercise substantially improves QOL in populations with serious diseases, such as cancer⁹ or chronic obstructive pulmonary disease,¹⁰ but the data are not as supportive in populations without disease. Although many, but not all, epidemiological studies have found an association between exercise and QOL, the available data from intervention trials fail to consistently find a strong effect of exercise training on QOL.^11,12 Furthermore, the data from intervention trials are difficult to interpret because of small sample sizes, inadequate control groups, and poor exercise compliance. In addition, many studies include a weight loss component, making it difficult to separate the benefits of weight loss from the benefits of increased exercise.

Calorie restriction (CR) increases longevity in numerous species¹ and, in nonhuman primates, it increases health span (length of time the organism is free of disease).^2-4 To our knowledge, the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE 2) trial is the first study to examine the effects of long-term CR on disease risk factors and predictors of longevity in nonobese humans. The design⁵ of CALERIE 2, recruitment methods,⁶ baseline data,^7,8 and intervention used to promote long-term (2-year) CR⁹ have been described elsewhere. Briefly, CR resulted in metabolic adaptation and improvements in chronic disease risk factors, indicating that CR may improve the health span of nonobese humans.⁷ These results raise the possibility that more people, including normal-weight people, might attempt to practice CR in an effort to increase lifespan and health span, yet concerns remain about potential negative effects of CR on psychological and endocrine outcomes.