More Popular Misconceptions

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There may be people who can gain weight on 1200 calories a day, but to say that

people on 1200 calories a day gaining weight has caused the obesity problem not

acccurate.

My personal experience with people is that they do misrepresent the amount of

calories they eat and/or have no clue to how many calories they consume each

day. But, when you begin to work with them or have them carefully track their

calories, 2 things usually happen; being accountable, they eat less, and being

accountable they become more honest. Somehow they " forget " about that bag of

chips or chocolate cake they eat and dont report it.

There are also other changes that may happen short term, that appear as weight

loss, or weight gain that may appear to violate the lawa of physics, but are due

to measurable changes in fluid volumes, glycogen stores, salt intake or fiber

amounts. One example is ....if 2 people consuming typical diets try to lose

weight, and they both do it by reducing calories equally, but one also cuts out

all carbs, while the other doesn't, the one cutting out all carbs can lose an

extra 4 or so pounds from glycogen and water losses.

With portions sizes growing and hidden fats and sugars in lots of foods, caloric

values and caloric density of foods have risen.

In the National Weight Control Registry, there are now over 4000 subjects who

have documented weight loss. The average weight loss is 65#s, maintained for ~6

years. Prior to their weightloss, the average BMI was 35, and now is 26.

The average caloric intake is 1382 Calories (1725 Men, 1300 Women).

On macronutrient ratios... in these studies below, changing macronutrient ratios

from very high carb to very low carb had no effect on weight as long as caloric

intake was maintained steady.. Diets, metabolism etc were carefully monitored.

Jeff

Diet composition and energy balance in humans.Am J Clin Nutr 1998 Mar;67(3

Suppl):551S-555S

Hirsch J, Hudgins LC, Leibel RL, Rosenbaum M.

Inpatient metabolic studies of human subjects were performed to obtain data on

important nutritional issues. It was shown that wide variations in the ratio of

carbohydrate to fat do not alter total 24-h energy need. Studies of the fatty

acid composition of plasma low-density lipoproteins during low-fat feeding

indicated that there can be considerable lipogenesis from carbohydrate in humans

during isoenergetic feeding. The energy cost of this conversion must be small or

be counterbalanced by other changes in energy metabolism because measured energy

need was unaltered by fat-to-carbohydrate ratios. Energy need was, however,

markedly varied by changes in body weight. Subjects at their usual body weights

who had experimentally induced increases in body weight became inefficient and

required a higher energy intake for weight maintenance. The reverse occurred

with a reduction in body weight. The set point at which energy storage is

defended is clearly different in obese persons.

Energy intake required to maintain body weight is not affected by wide variation

in diet composition.

Am J Clin Nutr. 1992 Feb;55(2):350-5.

Leibel RL, Hirsch J, Appel BE, Checani GC

Diets rich in fat may promote obesity by leading to a greater deposition of

adipose-tissue triglycerides than do isoenergetic diets with less fat. This

possibility was examined by a retrospective analysis of the energy needs of 16

human subjects (13 adults, 3 children) fed liquid diets of precisely known

composition with widely varied fat content, for 15-56 d (33 +/- 2 d, mean +/-

SE). Subjects lived in a metabolic ward and received fluid formulas with

different fat and carbohydrate content, physical activity was kept constant, and

precise data were available on energy intake and daily body weight. Isoenergetic

formulas contained various percentages of carbohydrate as cerelose (low, 15%;

intermediate, 40% or 45%; high, 75%, 80%, or 85%), a constant 15% of energy as

protein (as milk protein), and the balance of energy as fat (as corn oil). Even

with extreme changes in the fat-carbohydrate ratio (fat energy varied from 0% to

70% of total intake), there was no detectable evidence of significant variation

in energy need as a function of percentage fat intake

Nutrient balance in humans: effects of diet composition.

Am J Clin Nutr. 1991 Jul;54(1):10-7.

Hill JO, s JC, GW, Schlundt DG, Sharp T, Greene HL.

The purpose of this study was to examine the effect of alterations in diet

composition on energy expenditure and nutrient balance in humans. Eight adults

(three men, five women) ate a high-carbohydrate (60% of calories from

carbohydrate) and a high-fat (60% of calories from fat) diet for 7 d each

according to a randomized, crossover design. Six subjects were studied for an

additional week on a mixed diet (45% of calories from fat). For each subject,

total caloric intake was identical on all diets and was intended to provide the

subject's maintenance energy requirements. All subjects spent days 3 and 7 of

each week in a whole-room indirect calorimeter. Diet composition did not affect

total daily energy expenditure but did affect daily nutrient oxidation by

rapidly shifting substrate oxidation to more closely reflect the composition of

the diet. These results show that diet composition can affect substrate

oxidation without producing measurable effects on total energy expenditure.