Weight loss correlates with low carb, not low calorie

This is extracted from: “The Obesity Epidemic: What caused it? How can we stop it?”

Marjorie R. Freedman, Janet King, and Eileen Kennedy wrote an article called “Popular Diets: A Scientific Review”, where 17 studies of weight loss with different macro nutrient (carbohydrate, fat and protein) composition, were reported with the concomitant results.[i] The authors stated that “no published studies are excluded”, so I have assumed that these are the only studies between 1956 and 2001. The three authors concluded “Caloric balance (calories in vs. calories out), rather than macro nutrient composition is the major determinant of weight loss.”

Yet I analysed all the data for these 17 studies and found no relationship between low calorie intake and high weight loss (0.009 correlation coefficient), but a significant relationship between low carbohydrate intake and high weight loss (0.79 correlation coefficient) (Tables below). How can the authors have concluded as they did, unless they set out to prove an already held point of view?

“Popular Diets: A Scientific Review”[i]

Authors & publication # of people Duration Carb grams/day Kcal/day grams lost/ day
1 Rickman, JAMA (1974) 12 7 days 7 1,325 -442
2 Benoit et al, Ann Intern Med (1965) 7 10 days 10 1,000 -660
3 Yudkin & Carey, Lancet (1960) 6 14 days 43 1,383 -200
4 Fletcher, Br J Nutr (1961) 6 14 days 36 800 -223
5 Lewis et al, Am J Clin Nutr (1977) 10 14 days 27 1,115 -371
6 Kasper et al, Am J Clin Nutr (1973) 16 16 days 56 1,707 -300
7 Evans, Nutr Metab (1974) 8 6 wk 80 1,490 -97.5
8 Golay et al, Int J Obes relat Metab Disord (1996) 22 6 wk 37.5 1,000 -212
9 Young, Am J Clin Nutr, (1971) 3 6 wk 30 1,800 -385
10 Golay et al, Am J Clin Nutr (1996) 31 12 wk 75 1,200 -121
11 Cedarquist, J Am Diet Assoc (1952) 7 16 wk 85 1,500 -114
12 Worthington & Taylor, J Am Diet Assoc (1974) 20 21 days 17 1,182 -571
13 Rabast et al, Int J Obes relat Metab Disord (1979) 13 25 days 48 1,871 -350
14 Rabast et al, Nutr Metab (1978) 25 30 days 25 1,000 -392
15 Wing et al, Int J Obes relat Metab Disord (1995) 11 4 wk 10 800 -270
16 Alford et al, J Am Diet Assoc (1990) 11 10 wk 75 1,200 -91
17 Baron et al, Am J Public Health (1986) 66 3 mths 50 1,000 -55

 

Notes:

*   21 studies were included in tables 5a and 5b in the paper. Three had no results for weight change, so could not be included (Kekwick 1957, Bortz 1968 and Krehl 1967).

*   I excluded Larosa et al (1980), as the table said that the study was for 12 weeks when, in fact, the article and the original journal revealed that the subjects followed their normal diet for two weeks at the start and two weeks at the end of the 12 week period. We cannot determine what the weight loss per day was in relation to a measured carbohydrate and calorie intake period.

*   The 17 remaining studies are above. There was a material error in the article. This has been corrected in the table above, as follows: Study 8 (Golay et al) – the weight loss in table 5a is given as -8.0 kilograms over 6 weeks, which was commuted to -111 grams per day in table 5a. This is wrong and -8.0 kilograms over 6 weeks equates to -190 grams per day. However, the table appears to be wrong in more way than one and the original journal (and the text in the article) state that the weight change for the group on 37.5 grams CHO was -8.9 kilograms +/- 0.6 kilograms. I have taken the mid point of -8.9 kilograms and this equates to -212 grams per day. This is the number in the table for this appendix and the number I have used for the correlation.

*   A number of ranges were taken at mid point level, as follows:

–    Study 7 (Evans) – the range of weight loss was given as -76 to -119 grams per day, so I took the mid point of -97.5 grams per day;

–    Study 11 (Cedarquist) – the range of weight loss was given as -78 to -150 grams per day, so I took the mid point of -114 grams per day.

*   Five of the studies were directly comparable isocaloric studies i.e. the studies had parallel groups on a different carbohydrate level and the same calories per day (these are studies 6, 8, 10, 12 and 14). In every such isocaloric study in the article, the weight loss was substantially higher in the low carbohydrate group than in the higher carbohydrate group. At the highest calorie intake (Kasper et al, study 6, 1707 calories per day), the group consuming 56 grams of carbohydrate per day lost 300 grams per day vs. the 156 grams of carbohydrate per day group, which only lost 50 grams per day. This supports Kekwick and Pawan’s findings that large numbers of calories can be consumed and weight still be lost with a low carbohydrate diet composition.

 

Correlation between (low) calories & (high) weight loss

  Authors Cals (x) Loss (y) x*y x*x y*y
1 Rickman 1,325 -442 -585,650 1,755,625 195,364
2 Benoit et al 1,000 -660 -660,000 1,000,000 435,600
3 Yudkin & Carey 1,383 -200 -276,600 1,912,689 40,000
4 Fletcher 800 -223 -178,400 640,000 49,729
5 Lewis et al 1,115 -371 -413,665 1,243,225 137,641
6 Kasper et al 1,707 -300 -512,100 2,913,849 90,000
7 Evans 1,490 -98 -145,275 2,220,100 9,506
8 Golay et al 1,000 -212 -212,000 1,000,000 44,944
9 Young 1,800 -385 -693,000 3,240,000 148,225
10 Golay et al 1,200 -121 -145,200 1,440,000 14,641
11 Cedarquist 1,500 -114 -171,000 2,250,000 12,996
12 Worthington & Taylor 1,182 -571 -674,922 1,397,124 326,041
13 Rabast et al 1,871 -350 -654,850 3,500,641 122,500
14 Rabast et al 1,000 -392 -392,000 1,000,000 153,664
15 Wing et al 800 -270 -216,000 640,000 72,900
16 Alford et al 1,200 -91 -109,200 1,440,000 8,281
17 Baron et al 1,000 -55 -55,000 1,000,000 3,025
Sum 21,373 -4,854.5 -6,094,862 28,593,253 1,865,057

 

Where:

N = the number of pairs of scores (17)

∑xy = sum of the products of paired scores (-6,094,862)

∑x = sum of x scores (21,373)

∑y = sum of y scores (-4,854.5)

∑x2 = sum of x scores squared (28,593,253)

∑y2 = sum of y scores squared (1,865,057)

r = 0.009

 

Correlation between (low) carbs & (high) weight loss

  Authors Carbs (x) Loss (y) x*y x*x y*y
1 Rickman 7 -442 -3,094 49 195,364
2 Benoit et al 10 -660 -6,600 100 435,600
3 Yudkin & Carey 43 -200 -8,600 1,849 40,000
4 Fletcher 36 -223 -8,028 1,296 49,729
5 Lewis et al 27 -371 -10,017 729 137,641
6 Kasper et al 56 -300 -16,800 3,136 90,000
7 Evans 80 -98 -7,800 6,400 9,506
8 Golay et al 38 -212 -7,950 1,406 44,944
9 Young 30 -385 -11,550 900 148,225
10 Golay et al 75 -121 -9,075 5,625 14,641
11 Cedarquist 85 -114 -9,690 7,225 12,996
 12 Worthington & Taylor 17 -571 -9,707 289 326,041
13 Rabast et al 48 -350 -16,800 2,304 122,500
14 Rabast et al 25 -392 -9,800 625 153,664
15 Wing et al 10 -270 -2,700 100 72,900
16 Alford et al 75 -91 -6,825 5,625 8,281
17 Baron et al 50 -55 -2,750 2,500 3,025
Sum 711.5 -4,854.5 -147,786 40,158 1,865,057

 

Where:

N = the number of pairs of scores (17)

∑xy = sum of the products of paired scores (-147,786)

∑x = sum of x scores (711.5)

∑y = sum of y scores (-4,854.5)

∑x2 = sum of x scores squared (40,158.25)

∑y2 = sum of y scores squared (1,865,057.25)

r = 0.79

I reiterate, how can the authors have concluded as they did, unless they set out to prove an already held point of view?

 

References

[i] Marjorie R. Freedman, Janet King, and Eileen Kennedy, “Popular Diets: A Scientific Review”, Obesity Research, (March 2001).

9 thoughts on “Weight loss correlates with low carb, not low calorie

  • avatar
    September 9, 2014 at 10:06 am
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    Hi Zoe, Was just searching the net and came across your blog. I am a medical doctor fed on calorie gibberish. However when i wanted to lose weight myself, i couldnt do that comfortably. So i did lot so self study and agree 100% with your observations.Hats off to you. I am now running an online Weight loss program with very good results.
    Please have a look at drvinayjadhav.com
    regards,
    Dr.Vinay
    INDIA

    Reply
    • avatar
      September 9, 2014 at 11:50 am
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      Hello India! How lovely to hear that we have a real foodie out East. Good luck to you – Zoe

      Reply
  • avatar
    September 2, 2014 at 4:42 am
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    What is ignored in the calorie debate is fibre. TV program Catalyst (ABC Australia) August 2014, 2-part series claims that massive intake of dietary fibre is a key to preventing disease. [http://iview.abc.net.au/programs/catalyst/SC1302H005S00 “In this two-part Gut Reaction special, reporter Dr Graham Phillips investigates whether the Western diet could be contributing to a whole litany of diseases by causing an imbalance in the bacteria deep inside our gut.” Transcript of part 1: http://www.abc.net.au/catalyst/stories/4067184.htm Part 2: http://www.abc.net.au/catalyst/stories/4070977.htm%5D
    Most high-fibre diets are low in fat.

    Reply
  • Pingback:La pérdida de peso está correlacionada con… | No vuelvo a engordar

    • avatar
      August 15, 2014 at 7:40 pm
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      Hi Vicente – so sorry for the late reply – just catching up on posts.
      I really enjoyed your post and it works well with pictures! Thanks so much for doing this and I hope many others see your link and enjoy the easier way of looking at this
      Very best wishes – Zoe

      Reply
      • avatar
        August 18, 2014 at 6:37 pm
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        Hi Zoe,
        I am glad you liked the graphs :)

        Yours sincerely,
        Vicente

        Reply
  • avatar
    August 7, 2014 at 8:27 pm
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    “Caloric balance (calories in vs. calories out), rather than macro nutrient composition is the major determinant of weight loss.” – Caloric balance!

    You analyse caloric intake… not really the same thing!

    For example:
    Study #9 Young, Am J Clin Nutr, (1971) says:
    “The retrospective reporting of activity would indicate
    that the average caloric expenditures of all groups were
    very comparable, about 3,400 kcal/day for groups A and C;”
    kcal-IN: 1800; kcal-OUT: 3400 kcal-DEFICIT: -1600

    Study #17 Baron et al, Am J Public Health (1986) says:
    “Mean baseline weight 78.0 ± 3.7 kg”
    Can’t find info on energy expenditure, but lets assume 2300 kcal
    kcal-IN: 1000; kcal-OUT: 2300 kcal-DEFICIT: -1300

    Reply
  • avatar
    August 5, 2014 at 11:34 am
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    Hmmm… Is it really legitimate to compare rates of weight loss (g/day)across studies, without taking into account the roughly ten-fold variation in study duration? If you look at the correlations between total weight loss, energy, and carbohydrate intakes, I think you will get a different answer…

    Reply

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