Final answer:
After three to four weeks of sustained dieting, Marilyn is most likely to experience a lower resting metabolic rate. Her body's adaptation to the reduced calorie intake results in a more efficient use of energy, making further weight loss more challenging. Exercise can mitigate this effect by increasing metabolic rate.
Explanation:
By dramatically reducing her daily caloric intake, Marilyn plans to lose a significant percentage of her body weight. However, research suggests that after three or four weeks of sustained dieting, the most likely outcome for Marilyn is d) have a lower resting metabolic rate. When individuals reduce their calorie intake significantly, the body adjusts by lowering its basal metabolic rate (BMR), to conserve energy. This adaptive response can make further weight loss more difficult, as the body becomes more efficient at using the energy it does receive.
Moreover, rather than experiencing a decrease in fat cell count, the fat cells tend to decrease in size but remain constant in number. This aspect can contribute to the common experience of regaining weight after ending a diet. It's also important to note that while dieting can cause initial weight loss, incorporating exercise can be beneficial as it raises the metabolic rate even when resting, potentially aiding the weight loss process.