Dr Jacob Wilson is director of the skeletal muscle and sports nutrition laboratory at the Department of Health Science and Human Performance at the University of Tampa.
Ryan Lowery is senior research scientist at Department of Health Science and Human Performance at the University of Tampa, with a focus on sports nutrition and supplementation.
In the Western world there is a prevailing mentality of wanting things instantly, especially in the field of fitness. We don’t have time to wait for the results of our hard work to be realised. We want to be lean and ripped yesterday, and not have to wait until tomorrow. This desire has led bodybuilders – and increasingly the average gym-goer – to go on drastic diets and introduce more cardio into their training to rapidly lose fat.
However, these catabolic stimuli place you in a state where muscle loss can occur, and can result in a decrease in metabolic rate with simultaneous increases in hunger and appetite. This poses a serious challenge known as the ‘energy gap’ and is your body’s way of resisting becoming shredded and maintain homeostasis.
The hunger game
The first step to combat this resistance is to reduce feelings of hunger and there are a number of ways to achieve this. One is to realise that your stomach has a ‘pressure’ sensor, which is effectively when your stomach senses the volume of the food you consume. Studies show that you will be full and stop eating once your gut senses a certain volume of food has been reached.
Therefore, when trying to lose weight, your diet should be based on low calorie, energy-rich, high-fibre foods, such as vegetables and lean protein sources. This will fill you up without consuming a lot of calories. For example, one cup of green veggies might be as low as 20 calories and only 4g of carbohydrates, whereas one cup of raisins is around 500 calories and 130g of carbohydrates.
Another great tip is to add volume to your foods with the addition of water and air, such as protein smoothies. This will aide that feeling full sensation and leave you less likely to be hankering for junk food.
The cardio conundrum
Once you have controlled your hunger, how can you combat the catabolic effects of cardio and cutting calories? With cardio, our lab in Tampa has shown that it decreases muscle in a dose-dependent fashion, specifically that 60 minutes of cardio resulted in greater muscle decrements than 20 minutes.
This led us to believe that you should keep your sessions short and intense. We recently conducted a study comparing 10-30 second all-out sprints for 4-10 repetitions against the traditional 60 minutes of steady state cardio. We found that the sprinting protocol actually increased muscle mass, while the long duration cardio group saw a decrease.
Additionally, research has shown that high-intensity interval training can result in more fat loss than traditional long duration cardio.
One of the most important nutritional factors you must consider when trying to shed fat is your protein intake. One study found that you should keep your ratio of carbohydrates to protein at about 1g to 1.5g per pound of bodyweight as a minimum while on a restricted diet. So, looking at your plate, one-third should consist of protein, one-third starchy carbohydrates, and one-third vegetables for bulk and volume.
While this is not the only method for getting you shredded, we do know from research that it spares muscle from being lost during a diet. And every meal needs to contain protein to minimise muscle loss. Research has found that the threshold for maximising protein synthesis is about 30-40g of protein per meal. This results in elevated protein synthesis and metabolic rate. We published a study where we found lower body fat in subjects who met this threshold more times throughout the day.
The rate of fat loss
Last, but certainly not least, we need to consider how rapidly you lose fat. Obviously, the rate you lose weight will be determined by how much you cut your calories. What you must understand is that the amount of muscle you lose will be related to how lean you are when dieting, and how rapidly you lose weight.
Simply put, when you have a higher body-fat percentage you preferentially burn fat as fuel, while those who are lean (under 10% body fat) will preferentially lose muscle if the calorie deficit is too drastic.
For example, one study found that those with a higher amount of body fat could cut their calories by greater than a thousand per day with minimal muscle loss, while leaner people lost the majority of weight from muscle at this deficit.
However, another study reported that a lower calorie deficit (<500 calories) resulted in minimal fat loss for lean individuals. This suggests that if you have a lot of bodyfat you can cut calories more aggressively early in your prep, and become more conservative as you lean-out. More recently, one study placed athletes on a weight-loss programme resulting in either 1lb or 2lb per week. Both groups lost the same amount of bodyweight, it just took longer to accomplish in the slow group.
Results showed that subjects in the fast weight-loss group lost a small amount of muscle and about 20% of their fat mass. However, the slow group lost over 30% of their fat mass but gained muscle.
In summary, if you start out lean (10-12%), then you might just lose 1lb a week throughout the first half of the cut and take your restriction more conservatively (½lb per week) thereafter. If, however, you start out with higher bodyfat (>15%) then you can start the diet a bit more aggressively (1-2lbs a week), and then slow the rate of weight loss as you approach 10%.
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