Every fat loss diet is simple. In fact, losing weight is easy. It's basic calorie math and willpower. Eat fewer calories or expend more calories than your maintenance intake, and the excess weight goes right down the shower drain. The devil, of course, lurks in the details.
First, you have to choose how you want to do your calorie math – what "flavor" of calorie deficit tastes best to you? Low or high carb? Some brand of calorie cycling or intermittent fasting? Vegetarian? Anything goes as long as calories are low enough?
It almost doesn't matter. Almost.
Personal preferences and dietary tribalism aside, lifters and athletes also want more than "weight" loss. You probably want to lose fat. JUST fat. You want to retain all the muscle you have and maybe even add a bit more.
You also want a sustainable diet that doesn't quickly lead to a plateau or fat regain, a diet that keeps your hormone levels and metabolic rate healthy, and one that doesn't completely wreck your gym performance.
The problem is, most "evidence-based" diets are derived from studies using overweight or obese folks who don't lift weights. These people have different needs and goals. Studies conducted on them often don't measure catabolic muscle loss, metabolic rate, or performance.
That's why a recent diet study from Bill Campbell, Ph.D., caught my attention. First, it used 27 lean athletes, a mixture of men and women involved in resistance training. Think: healthy people who want to further improve appearance and body comp. Second, muscle preservation and resting metabolic rate were measured.
In short, the 7-week diet was a success for those who finished it: body fat was lost, muscle was retained, metabolic rate was better maintained, and gym performance wasn't hampered.
Two groups were studied. Both did the same workouts. One group used a typical diet plan – they reduced calorie intake by 25% a day for seven weeks. That's called a "continuous diet."
But it's the other group we're interested in: the non-linear diet or refeed group. Here's an overview of the more successful, non-linear plan:
- Reduce calories by 35% for 5 days, Monday through Friday.
- Go back up to maintenance calories on Saturday and Sunday.
- Consume about .8 grams of protein per pound of body weight on all days (1.8g protein/kg body weight). That means a 200-pound person would consume around 164 grams of protein per day. The remaining calories are split evenly between fat and carbohydrate.
- On the weekend refeed, where you jump back up to maintenance intake, the additional calories come from carbs.
- Lift weights 4 days per week during weeks 1-3 and 5-7. During week 4, lift weights twice. (This is a back-off week – a planned reduction in training volume.) Study participants used two upper-body focused workouts and two lower-body focused workouts per week, not counting the fourth week. Exercises were all basic barbell, dumbbell, and machine movements.
- Do low-to-moderate intensity cardio twice per week (running, cycling, swimming, rowing, etc.). Perform this at a pace where you could easily have a conversation.
- On lifting days, consume 25 grams of protein powder after training. (Study participants used whey protein isolate.)
In the study, both groups – continuous and non-linear – reduced calories by a total of 25% per week. The non-linear group just achieved that by dieting "harder" on weekdays (35% reduction) and going back up to maintenance numbers on weekends by adding carb-derived calories.
While both groups lost fat, the weekend refeeders lost a bit more, preserved their fat-free mass (muscle), and better maintained their resting metabolic rate. In other words, the non-linear plan prevented catabolism and helped keep their metabolisms chugging along.
This is huge because previous studies on non-overweight athletes show that losing muscle – muscle protein breakdown – can occur even with a 10-day diet of 20% calorie restriction.
So how did the refeed strategy prevent the loss of fat-free mass if total weekly calorie reduction was about the same in both groups?
- The two-day uptick in calories could have blunted the catabolic environment for muscle. Maybe it's not a good idea to stay in a caloric deficit for longer than five days in a row?
- The two-day carb refeed may have resulted in more glycogen stored in the muscles. That could've led to less fatigue and more effort during training.
- The additional weekend carbs could have caused insulin secretion, which suppresses acute muscle protein breakdown.
Whatever the reason, non-linear dieting looks like the better choice for lifters chasing physique enhancement and body composition goals.
If you don't want to adopt the whole plan, you can still take home some general strategies:
- Never diet without lifting weights. That's what regular people do, and they usually yo-yo.
- Never do a low-protein diet. Reduce the calories from fats and carbs; keep protein on the higher side. If you hate converting between kgs and pounds, eating about a gram per pound of body weight every day does the trick. A quality protein powder – consumed as a shake or added to foods – can make that easy to do.
- Calorie cycling and perhaps carb cycling (periodic two-day refeeds) work better than just reducing calories linearly throughout the duration of a diet. Keep in mind, these aren't "cheat" days, just a brief return to maintenance. That weekend boost is also a nice mental and social break from the stricter weekdays, which should help with compliance and consistency.
Also, while it hasn't yet been scientifically tested, the researchers are interested in seeing what happens when you re-feed for 24-hours every third day: diet for two days, bump up to maintenance for a day, diet for two days, repeat.
Give it a shot. Your body is your laboratory.
- Campbell B et al. Intermittent energy restriction attenuates the loss of fat-free mass in resistance-trained individuals. A randomized controlled trial. Journal of Functional Morphology and Kinesiology. 2020 Mar 8;5(1):19.