These aerobics instuctors are too-often elevated to positions where they are considered 'the authority' in that gym for all types of fitness. It's amazing that these people are hired and put into positions of authority, where they can misinform those who come to them for guidance. These clients' very lives are greatly influenced by the bad information they receive. Any fitness club owner who employs instructors such as this should either re- train them or replace them. It's well known by some who have studied the situation, that the proper way to control body weight is to develop larger muscles.
Muscles are the engines that burn the fuel, calories.
While aerobics burn a higher number of calories during the exercise and for a short time afterwards, a well-muscled body burns more calories 24 hours of every day. Furthermore, when anyone cuts down on their caloric intake, even though they might do aerobic exercises ferociously, their body goes into super-efficient starvation mode to protect itself from being decimated. Strength training reverses this effect by cranking up the metabolism to burn more calories. As regarding strength training and our senior citizens, it would seem that the medical profession has blinders on. It only stands to reason that anyone of any age who is frail and weak should be advised to find ways to make themselves stronger, lest they become so frail and weak that they die.