Short periods of fasting could help people lose weight and lead to better health.
本题考查对并列连词的使用。
并列，指由并列连接词将同级的两个语言单位连接而成。由题干可知两句话的主语都Short periods of fasting，所以合并主语，用并列连词and来连接两个禁食的好处，could后面的动词用原形，所以是could help people lose weight and lead to better health.
句意：短时间的禁食可以帮助人们减轻体重，使身体更健康。
