Exercise alone is unlikely to help shift the pounds, say researchers.
Researchers at Bangor University in the United Kingdom found that women who engaged in exercise classes three times per week for 4 or 8 weeks — but who did not change their diets — failed to lose any weight.
Study co-author Dr. Hans-Peter Kubis, of the School of Sport, Health & Exercise Sciences at Bangor University, and colleagues recently reported their findings in the journal Applied Physiology, Nutrition, and Metabolism.
The study involved two experiments. For the first experiment, 34 women aged 18 to 32 years took part in a circuit exercise training session three ti
mes per week for a total of 4 weeks.
The second experiment included 36 women of the same age group, all of whom took part in the same training sessions, but for a total of 8 weeks.
At the beginning and end of each experiment, the weight, muscle, and fat mass of each woman were measured.
Blood samples were also taken from the participants, which allowed the team to measure levels of appetite hormones, including insulin, leptin, amylin, ghrelin, and peptide YY. Such hormones can influence feelings of hunger and food intake.
Appetite hormones may play a role
The aim of this study was to determine whether or not exercise alone would lead to weight loss in the women, but the subjects were not informed of this. Instead, they were told that the study would assess the effects of exercise on cognition and cardiorespiratory fitness. Dr. Kubis says that this was to avoid potential bias.
“When people take up exercise, they often restrict their diet — consciously or unconsciously — and this can mask the effects of the exercise,” he explains.
At the end of the 4- and 8-week programs, the researchers found that none of the women had lost weight, regardless of whether they were lean, overweight, or obese prior to the intervention.