Exercise is plagued with common misconceptions and/or poor information. This page clears some of these up.
Pop fitness magazines and articles continue to spread the pervasive myth that juice cleanses help to "detoxify" the body.
First, what exactly is a juice cleanse?
Most gymnasts are short because of a simple filtering effect: the shorter the gymnast, the more advantage they have, the more successful they are, the more likely they are to continue gymnastics. The inverse is also true: the taller the gymnast, the less advantage, less success, less likely to continue. This leads to the notion that gymnastics stunts growth.
The 2013 paper, Role of Intensive Training in the Growth and Maturation of Artistic Gymnasts:
The International Gymnastics Federation (FIG) asked four questions related to the relationship between stunted growth and gymnastics training:
(1) Is there a negative effect of training on attained adult stature? (2) Is there a negative effect of training on growth of body segments? (3) Does training attenuate pubertal growth and maturation, specifically, the rate of growth and/ or the timing and tempo of maturation? (4) Does training negatively influence the endocrine system, specifically hormones related to growth and pubertal maturation?
The study concluded (from the abstract):
Gymnasts as a group demonstrated a pattern of growth and maturation similar to that observed among short-, normal-, late-maturing individuals who were not athletes. Evidence for endocrine changes in gymnasts was inadequate for inferences relative to potential training effects. Allowing for noted limitations, the following conclusions were deemed acceptable: (1) Adult height or near adult height of female and male artistic gymnasts is not compromised by intensive gymnastics training. (2) Gymnastics training does not appear to attenuate growth of upper (sitting height) or lower (legs) body segment lengths. (3) Gymnastics training does not appear to attenuate pubertal growth and maturation, neither rate of growth nor the timing and tempo of the growth spurt. (4) Available data are inadequate to address the issue of intensive gymnastics training and alterations within the endocrine system.
The conclusion from the 2008 paper Growth and Maturation of Adolescent Female Gymnasts, Swimmers, and Tennis Players:
results from this study suggest that regular training did not affect final adult stature and that, when aligned by biological age, the tempo of sexual maturation was similar in these young athletes.
It is common advice to not go below 90° (angle at the knee between the calf and thigh) when squatting for fear of injuring the knee. Yet Olympic weightlifters regularly squat deep (also called ATG, or ass-to-grass) without knee issues.
Hartmann et al's Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load examines the forces on the knee (and spine) at different flexion angles. From the abstract:
There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar [area where "patella (kneecap) and the femur (the thigh bone) meet] compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces [the deeper the squat, the lower the forces].
While one study isn't conclusive proof, the sheer amount of weightlifters who squat ATG is.
More information on the squat and its safeness can be found here.
Losing weight is an incredibly simple for most people: intake fewer calories than you expend. Caloric expenditure can be found by your total daily energy expenditure (TDEE), the amount of calories you burn by existing, exercising, and eating.
This fails to take into account the quality of the diet, meaning you can eat all the Twinkies, Oreos, Doritos, and Little Debbies you want and still lose weight.
There are absolutely differences in bone sizes, and thus "frame sizes", which can be found here. However, people often use this to justify being overweight.
For women, large frames correspond to wrist sizes of >5.75", 6.25", and 6.5" for <5'2", 5'2"–5'5", and 5'5", respectively. For men, large frames correspond to any wrist size over 7.5". Wrist sizes are fairly stable across people regardless of weight, meaning they correspond well to frame size.
Bone mass as a percentage of total bodyweight stays relatively constant across genders—15% is the commonly-cited value for males. Bone density also appears to be relatively stable across gender and age (see columns five and six in Table 1). Assume the average is 1.15 g/cm3.
Take a 80 kg = 80000 g male with average bone density. Their total bone mass is thus 80,000 g × 0.15 = 12000 g, and total bone volume is 12000 g / 1.15 g/cm3 = 10,500 cm3.
Now, taking a so-called "big-boned" person with the same bone density, but 1.25x total bone volume, the extra weight is: 10500 cm3 × 1.25 & times 1.15 g/cm3 - 12000 g = 3000 g = 3 kg = 7 lb. This is a fairly insubstantial amount of weight gained due to large bones. (In fairness, I couldn't find any info on how much more bone volume large frame people have, so the 1.25 factor is arbitrary, but 1.5 felt like way too much.)
This 7 lb is not close enough to significantly change a person's BMI from healthy to unhealthy—that requires at least 28 lb (from "Normal" to "Obese").
See also: