And to back up my previous message
From The Ketogenic Diet book by Lyle McDonald (thanks Lyle
)
In a very low-calorie diet situation (VLCD, 800 calories per day or less), there are significant changes compared to higher calorie levels. VLCD without exercise causes a large drop in LBM and metabolic rate. The addition of aerobic exercise alone does not improve fat loss or prevent the drop in LBM and metabolic rate (27-30).
In severe dieting situations, aerobic exercise may actually be worse than just dieting(health benefits excepted). In one study, the addition of aerobic exercise (27 hours total over 5 weeks) to a very-low-calorie ketogenic diet (500 cal/day) caused a greater drop in metabolic rate than dieting alone and caused no additional weight or fat loss (29).
It appeared that the body compensated for the aerobic exercise by slowing metabolic rate at other times of the day. When resistance training only is added to an 800 calorie diet, muscle size increases despite a similar loss in LBM in both the diet only and diet plus exercise groups (31). This implies that the loss in LBM is due to loss of water, glycogen and other non-muscle tissues (32). Metabolic rate still goes down.
The conclusion from this data is this: on a VLCD, weight training but not aerobic exercise will slow the drop in metabolic rate but not stop it. The inclusion of aerobic exercise may do more harm than good at this calorie level.
Summary (snipped)
There is a caloric threshold for exercise to improve the rate of fat loss. A calorie deficit more than 1000 cal/day will slow metabolism. Further increases in energy expenditure past that level does not increase fat loss (14). In some cases, excess exercise will increase the drop in metabolic rate seen with very large calorie deficits.
This value of 1000 calories per day includes any caloric deficit AND exercise. Meaning that if 500 calories per day are removed from the diet, no more than 500 calories per day of exercise should be performed. If someone chose to remove 1000 calories per day from their diet.
27. Van Dale D et. al. Does exercise give an additional effect in weight reduction regimens. Int J Obes (1987) 11: 367-375.
28. Hill JO et. al. Effects of exercise and food restriction on body composition and metabolic rate in obese women. Am J Clin Nutr (1987) 46: 622-630.
29. Phinney SD et. al. Effects of aerobic exercise on energy expenditure and nitrogen balance during very low calorie dieting. Metabolism (1988) 37: 758-765.
30. Phinney SD. Exercise during and after very-low-calorie dieting. Am J Clin Nutr (1992) 56: 190S-194S.
31. Donnely JE. Muscle hypertrophy with large-scale weight loss and resistance training. Am J Clin Nutr (1993) 58: 561-565.
32. Marks BL and Rippe J. The importance of fat free maintenance in weight loss programs.
Sports Med (1996) 22: 273-281.
33. Sweeny ME et. al. Severe vs. moderate energy restriction with and without exercise in the treatment of obesity: efficiency of weight loss. Am J Clin Nutr (1993) 57: 127-134.
Think I have all the right references here, though there are probably more.
BTW, the ketogenic diet book, isn't a diet, but a book about ketosis. Lyle is an expert in his field (ketosis/vlcd/exercise.
I have no idea of Cambridge's view on this...whether they agree or disagree.