When I say crashing your metabolism I mean stalling your fat loss. Mark talks about this in TSPA.
When these people stall (and they inevitably do), they panic and further cut back on food intake. They'll lose fat for another few days or a week and stall once again. At this point they either quit or crank up their cardio to INSANE, unecessary, MUSCLE_WASTING proportions. this actually proves counter-productive. Their body slows its metabolism, and from this point on any further fat loss is accompanied by a corresponding loss in muscle mass.
The number one thing your body is designed to do is keep you alive for as long as possible when it thinks your starving to death. If you have 40% body fat you can drop calories and not really have to worry about your body thinking you’re starving to death because it knows you have a lot of fat and you’re in no danger of dying from starvation. When you get to lower body fat levels, in the teens, and you’re dropping to single digits for a bodybuilding competition your body knows you don't have a lot of fat and thus will do everything in its power to stop you from losing that small cushion of fat you have left. Leptin is the primary trigger by which your body measures body fat.
The following is a great explanation of Leptin and how it works and the reason when your cutting body fat that low you need to do carb ups to trick the body into thinking it’s not starving and keeping your metabolism high and burning those last few pounds. If you don't do this your metabolism will stall (crash) and you will stop losing.
Leptin
Leptin is a Protein hormone responsible for sending a signal to the brain to indicate how much fat we have in reserve and how many calories we have coming in. Leptin is released primarily from the fat cells and the level of Leptin in the body is directly proportional to the amount of body fat we are carrying. The higher the level of body fat, the higher the level of Leptin in the body. As body fat levels drop, Leptin levels also decline.
It is widely understood that the body attempts to maintain a “set point” with regard to body weight. Leptin is a key player in maintaining this set point. When we begin dieting and the body enters a state of caloric deficit, Leptin levels immediately begin to drop. Levels of Leptin can drop as much as 50% within 48 hours of beginning a diet. This drop in Leptin triggers a chain of events designed to maintain the body’s set point and prevent the body from losing weight. Steps in the chain of events to prevent weight loss include; decrease in the levels of brain dopamine, increase in hunger, increase in circulating Cortisol, decrease in thyroid hormone output, decrease in production of testosterone, and decrease in overall metabolic rate.
It can clearly be seen that this chain of events is counterproductive to our bodybuilding goals of maximizing fat loss and maintaining lean muscle. Therefore minimizing the drop in levels of Leptin when dieting is certainly key to reaching our goal of a lean muscular physique.
Ghrelin
Ghrelin is a hormone released from the stomach that is directly responsible for stimulating hunger. Studies suggest that the body’s release of Ghrelin actually adapts according to meal frequency and is a major reason that a person dieting becomes hungry in advance of regular meal times during the day. Increases in the release of Ghrelin cause increased hunger, increased fat storage and decreased overall metabolism. Levels of Ghrelin in the body are closely related to levels of Leptin. As Leptin levels fall, levels of Ghrelin increase. Therefore, as your body senses a caloric deficit and a decrease in stored fat, it signals an increase in the release of Ghrelin to stimulate hunger, and to decrease your metabolism; talk about counterproductive to your goals!
In addition to Leptin and Ghrelin, other hormones such as insulin, peptide YY, and also play significant roles in fat metabolism and anabolism and decreasing lipolysis when the body is in a state of prolonged caloric deficit. insulin secretion and sensitivity and it’s specific role in anabolism and fat metabolism will be the topic for part 2 of this series.
With our bodies seemingly fighting us right from the start when we begin to diet, how can we ever succeed? Fortunately, we have a method to combat these hormonal signalers that seek to derail our plans to get ripped. The secret weapons in our nal are carbs and calories! That’s right, when used properly the much maligned carbohydrate can help us prevent the reduction in Leptin levels and rise in Ghrelin levels which would otherwise stop our fat loss in it’s tracks.
The key to maintaining fat loss and keeping the hormones responsible for fat metabolism in the optimal ranges while dieting is the cycling of lower carb and calorie days with periodic higher carb and calorie days at regular and specific intervals. Increasing your carbs and calories in a planned and controlled fashion can and will help you burn more fat.
Cycling Your Carb Intake
Increasing total carbohydrate and calorie intake for one day, every 4-7 days during a contest prep diet can significantly increase Leptin levels and decrease Ghrelin levels preventing downregulation of the body’s metabolism. It’s important to note that increased carbohydrates are necessary for this process to occur. Simply increasing total calories without increasing carb intake does not create the same effect. Increasing carbohydrate consumption once every 4-7 days also has the added benefit of replenishing intramuscular glycogen stores and improving intramuscular cellular hydration.
