Wednesday, August 30, 2017

Shed 25% Extra-Fat (1.6kg/12Wk) + Improve Glucose Levels by Adding 2.5h/Wk of Walking to Your/Clients' Fatloss Diet/s

The amount and quality of food you eat determine how much weight you will lose, the quantity and quality of exercise controls how much of your weight loss is going to come from body fat.
One of the biggest mistakes a coach can make is to overwhelm his clients with taxing workouts that ruin their already low "excitement" for getting off the couch altogether. I've previously discussed studies that show: especially in people who still have a ton of weight to lose intense workouts are not necessary to accelerate clients' weight loss and promote fat over lean mass loss.

A recent study from the universities of M√ľnster and Bonn (both in Germany) provides additional evidence in favor of the prowess of low-intensity exercise as a weight- and, more importantly, fat loss promoter.
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The scientists' proclaimed goal was to investigate the effects of an energy-restricted diet with and without light-intensity feasible exercise in form of moderate walking on body weight, body composition, resting energy expenditure (REE), and endocrine and cardiometabolic risk variables in overweight and obese participants.

Figure 1: Flow diagram of the study design (Kleist 2017).
To this ends, the scientist recruited 82 obese and overweight men and women [mean baseline characteristics: age, 39.4 y; weight, 99.3 kg; body mass index (in kg/m²), 31.9] for a 12-wk, randomized, 2-arm, parallel, controlled, energy-restricted (500–800 kcal/d) dietary intervention study.

Participants were divided into two groups. One group received a hypo-energetic diet (DI | 500-800kcal/d deficit; 1.0g/kg protein;  22–25% protein, 42–45% carbs, 32–35% fat. ) only (n = 44). The second group received the same DI and participated in a regular walking program of 2.5 h/wk (DI + walking; n = 38).

The diet contained less than 15% saturated fat (as % of total fat) and was based on conventional, mixed foods. The main components were low-fat foodstuffs, e.g., whole-grain bread and cereals, vegetables, and fruits.

Quality counts: A particular emphasis was put on the intake of lean, protein-rich foods, such as lean meat and fish, skimmed milk, and low-fat dairy products. Furthermore, participants were encouraged not to eat highly processed and fried food.

To  make it easier for the subject to adhere to the diet, all recommended foodstuffs were divided into different groups (bread, rolls, and cereals / starchy side dishes (e.g., pasta, potatoes, rice) / milk and milk products/meat and meat products/fish and fish products/fruits/salad and raw vegetables / cooked vegetables/fats, oils, and dressings | see Figure 2):
Figure 2: Food groups for recommendations the subjects could choose from (Kleist 2017).
For products (e.g., milk or yogurt) within each group, specific quantity targets were calculated, so that the participants could choose day by day from different products - a facilitation of which the authors believe that it contributed significantly to the subjects' dietary adherence.
The subjects were not on a high-protein diet, but... it is quite striking that the absolute protein intake during the intervention phase was identical to the subjects' habitual protein intake. In that, the 1.0g/kg still aren't "high protein" (at least not by the fitness community definition), but it is certainly noteworthy that the caloric deficit was achieved solely by reducing the carb and fat intake by 105g and 57g per day, respectively - the protein intake, on the other hand, was kept stable.
A similar reasoning probably underlay the scientists' decision to prescribe a very manageable physical activity program consisting of "only" three hours of brisk walking per week. Those 3h were the sum of at least one weekly 1h outdoor walk and two walks on a treadmill - all at a mean speed of ca. 6 km/h, which was measured by the means of a professional sports watch (SUUNTO t3c Black Arrow) and foot-pod (SUUNTO Foot Pod mini).

If you are in a caloric deficit, you'll lose weight - no matter if you work out or not.

As you would expect from an energy-restricted diet participants actually adhere to, the intervention worked: After the 12-wk intervention, body weight was significantly decreased in the DI + walking group and the DI group (−8.8 compared with −7.0 kg, P = 0.064 for intergroup differences).
Figure 3: Changes in body weight, composition and insulin resistance after 12 wks DI +/- Walking (Kleist 2017).
What is more important than the non-significant increase (1.8 kg | 20%) in body weight loss, though, is that this decrease in body weight was accompanied by a significant reduction in total fat mass, which was significantly more pronounced in the DI + walking group than in the DI group (−6.4 ± 3.1 compared with −4.8 ± 3.0 kg; P = 0.020).

In this context, it is also worth mentioning that insulin and the homeostasis model assessment of insulin resistance index (HOMA-IR) were significantly reduced only in the DI + walking group. 

The significant reductions in serum free triiodothyronine (T3) and resting energy expenditure (REE) due to the energy restriction, on the other hand, was not significantly affected by the "exercise" regimen (it is worth mentioning, however, that the absolute values were small for both groups: -29kcal/d and -0.16 pg/ml for DI + walking and -72kcal/day and -0.12 pg/ml for DI). Similarly, diastolic blood pressure, mean arterial pressure, LDL cholesterol, and non-HDL cholesterol were significantly improved by both interventions, while the levels of cortisol increased (p < 0.05) - all without a significant inter-group difference.
Speaking of things trainers should do. If your clients or you yourself still believe that spending money on a (good) trainer was a waste of money, have them read/read this SuppVersity Classic: "Want to Double Your Gains? Get a Trainer to Kick Your Lazy Ass!"
Bottom line: "It doesn't always have to be a super-intense workout, to ..." I think I've written that before, and the study at hand further supports this statement. The less trained and the further off of a healthy weight your clients or you, yourself, are, the more effective will even light "exercise" interventions... and/or increases in non-exercise physical can be.

By the way, even though the study at hand dealt with overweight/obese untrained subjects, there's still a takeaway message for athletes and their coaches, as well: it's the diet that's driving the weight loss, it's your training (and to a very small degree supplements) which ensure that what you lose is predominantly fat.

That a combination of "cardio" (or non-exercise physical activity, which is imho what the walking in the study at hand was) and weight training would probably yield superior improvements in body composition goes without saying, right? Comment!
  • Kleist, Bernadette, et al. "Moderate Walking Enhances the Effects of an Energy-Restricted Diet on Fat Mass Loss and Serum Insulin in Overweight and Obese Adults in a 12-Week Randomized Controlled Trial." The Journal of Nutrition (2017): jn251744.