Guest Article – Meal Timing By Sean Armstrong
Currently, there are many dietary trends that are circulating around the interwebs with a zealot like following; Intermittent fasting, carbohydrate back loading, carb nite and a so-called ‘warrior diet’ for real badasses. Basically the latter is eating at the end of the day everyday. I personally like lunch, so no thanks Jeff. But do these dietary protocols have any scientific basis to their benefits to body composition? As their cult like following suggest? It should be mentioned that once upon a time I was a intermittent fasting advocate but we will come back to that later on or at the end, so it cant be suggested that I’m biased. I will mention that it did help me shift 30lbs though.
Recently, it was found that those that ate late lunches (LL) lost less weight and displayed a slower weight-loss rate during a 20-week dietary intervention compared to those that ate lunch earlier (EL) (Garaulet et al., 2013). Apparently both groups had achieved similar intakes of energy with the LL group eating a measly 38kcal’s fewer calories per day, which is hardly significant or worthy of note. The issue however is the method of obtaining energy intake in groups, ‘7 day dietary records’ were used. This limits the credibility of research due to lack of dietary control. It is well know that using self-reported diet intake, leads to underreporting of food intake (Yanetz et al., 2008) and the degree of which can come down to other factors. More importantly, gender is one of these factors (Garriguet, 2008). This may suggest the greater likelihood of underreporting in the LL group as 54.8% were women compared to 44.9% in the EL group and as women are more likely to underreport food intake more than men, you can see what I’m suggesting (sorry ladies). The thing that makes me chuckle the most is the lack of real world difference, the EL group lost an additional 0.11kg in weight per week or even better a poor 15g per day. Considering the EL had a higher BMI, it would be wise to assume that they also had a greater starting weight and a higher metabolic rate. Considering that energy intake is apparently matched it could suggest more weight loss is seen in the EL group as they are in a greater energy deficit. Whilst it has already been suggested that weight was not mentioned it could only be assumed that the dietary interventions failed to meet the RDA of protein (0.8g per kg of bodyweight) as the average intake between groups was only 65.95g. This intake fails to meet intakes that would be typically observed in us fitness enthusiasts and the applicability is therefore further reduced.
However, Jakubowicz et al. (2012) showed that after 16 weeks there were no significant differences in weight loss when a greater intake of energy (kcal) was consumed at breakfast compared to those that consumed a greater amount at dinner. The lower energy intake at breakfast and higher energy intake at dinner (also the lower carbohydrate group) did show modest increases in weight loss observed though (15.1kg vs 13.5kg) which funnily enough only translates to an additional 14g of weight loss per day. With the lower carbohydrate/higher energy intake at dinner being modestly more effective in terms of weight loss, it should be noted that they did have an overall increased protein intake compared to their higher carbohydrate/higher energy intake breakfast counterparts. This does have strength due to its large sample size (144 vs 10) compared with Keim et al. (1997) although it comes at the expense of the dreaded self-reported monthly dietary records. Which reduces the validity and reliability of the dietary interventions. Although, one strength of this research was the high protein intake. This was more than adequate for the sparing of muscle tissue and the promotion of satiety and is a intake more commonly seen in resistance-trained individuals.
|HCb Women||LCb Women|
|Kcal||gCHO(%)||gPRO (%)||gFat (%)||Kcal||gCHO (%)||gPRO (%)||gFat (%)|
|Breakfast||600||60 (40)||45 (30)||20 (30)||300||10 (13.3)||30 (40)||16 (48)|
|Lunch||500||10 (8)||70 (56)||20 (36)||500||10 (8)||70 (56)||20 (36)|
|Dinner||300||8 (10.7)||45 (60)||10 (30)||600||16 (10.6)||90 (60)||20 (30)|
|Total||1400||78(19.6)||160 (48.6)||50 (32)||1400||36 (10.6)||190 (52)||56 (38)|
|HCb Men||LCb Men|
|Breakfast||600||60 (40)||45 (30)||20 (30)||300||10 (13.3)||30 (40)||16 (48)|
|Lunch||600||12 (8)||84 (56)||24 (36)||600||12 (8)||84 (56)||24 (36)|
|Dinner||400||11 (10.7)||60 (60)||20 (30)||700||19 (10.6)||105 (60)||23 (30)|
|Total||1600||83 (19.5)||189 (48.7)||64 (32)||1600||41 (10.7)||219 (52)||63 (38)|
Other research has also shown similar findings to the previous studies. Sofer et al. (2011) compared the effects of carbohydrates eaten mostly at dinner or eaten throughout the day. As typical the diets provided or suggested were hypocaloric. Hypocaloric refers to a diet were participants eat less calories than burnt and was the case in 78 Israeli police officers, diets were prescribed as 1300-1500kcal (40-50% CHO, 20% PRO & 30-35% FAT). Those that ate the majority of their carbohydrates in the evening lost more weight and body fat compared to those who evenly consumed carbohydrates throughout the day. Again though, dietary intake was self-reported, leading to possible inaccuracies. This can be multiplied due to the effects of the dietary protocols on leptin. Leptin is a long-term satiety hormone, which decreased to a lesser extent in the evening carbohydrate group compared to the control group. With leptin being lower in the control group, it would be wise to assume that this group had an increased energy intake and may be the genuine factor to why weight loss was not as successful. Nevertheless, it appears that carbohydrates in the evening offer positive effects in hormonal and health biomarkers. The change in weight loss per day again was not even worth the extra planning or preparation required for a measly 14g per day of extra weight loss. This study however appears to be the weakest out of the lot in terms of protein intake (only because weight was actually declared and I could work this out). For this group of participants to be meeting the RDA they need to be consuming 78.64g of protein daily unfortunately 20% of their energy came from protein, which would only equate to 65-75g. Unfortunately, another study has failed to even provide a minimum requirement of protein limiting the applicability of the data to the fitness population.
Fortunately, other studies have controlled participant’s dietary intake. They also had participants undergoing both resistance and aerobic exercise during the intervention making it more applicable to the active fitness community which is you! Keim et al. (1997) observed that those that ate a greater proportion of their energy total (70%) in the AM lost more weight than those that ate the majority of their energy in the PM (70%) in a 6 week dietary intervention. This is the only study that supports the overly simplistic instagram picture. However, body composition appeared to have favourable changes when the majority of calories were instead ingested in the evening. This resulted with a further 0.69 % reduction in body fat percentage. The PM group lost more body fat and less lean body mass compared to their AM counterparts. Unfortunately this was measured with the use of total body conductivity. Total body conductivity is similar to bioelectrical impedance analysis and is highly sensitive to participants’ hydration status. This limits the validity and reliability of this body composition analysis in an obese population (Pateyjohns et al., 2012). These findings supports the theory that during the morning you are more primed to store energy as fat due to increased insulin sensitivity in both muscle and fat cells compared to later in the evening (Morris, Aeschbach & Scheer, 2012). Insulin sensitivity refers to the cells ability to take in glucose, which is beneficial in muscle cells. Although, it may lead to additional fat storage if fat cells are also sensitive and do absorb the present glucose. Nevertheless, comparable weight loss (3.9 vs 3.27 kg) and fat loss (2.9 vs 3.69 kg) was seen between groups. This difference again was minimal and just as a further point lets break it down to daily differences-15g extra weight loss per day is seen in the morning group. Hardly worth the extra effort to configure your diet like the experimental procedure, is it? Especially when you lose more lean body mass. This loss of lean body mass may due to the insufficient protein intake whilst in these hypocaloric conditions and perhaps would not be observed if protein met recommendations of 1.4-2.2g per kg of bodyweight. At least it was greater than the RDA with the intake coming in at 1.1g per kg of bodyweight.
This demonstrates that whilst timing may have importance although negligible, really the underlying thing that matters in physique enhancement and body composition is indeed the control of energy intake and enforcing a calorie deficit. Is it really necessary to use these strategies for physique enhancement when the returns are as little as an additional 14-15g of weight loss per day? It is strange that all these procedures had this minor effect; maybe it is magical? Moreover, focusing on these details is unnecessary when you consider the weaknesses of the research in regards to the lack of dietary control in the majority of the research and the lack of applicability to us as strength or physique athletes or enthusiasts due to incomparable protein intakes. It would be interesting to see how the results would go when protein was matched and at higher intakes than seen in Garaulet et al. (2013), Sofer et al. (2011) & Kiem et al. (1997). I would hazard a guess that no major differences would be observed. Worrying about the placement of the majority of your food, energy or macronutrient intake is worrying about the minutia. This is the phenomenon of placing the cart before the horse. Perhaps that silly instagram picture would have been more accurate if it reversed the order of biggest meals or better yet-don’t even post a simplistic picture up in the first place.
The time and sizes of your meals should always come down to personal preference and should adhere to the goals of the individual in terms of energy balance and macronutrient quantities. There is no real significant benefit to eating a bigger breakfast or bigger dinner, both provide similar rates of weight loss. When I look back at my previous love for (IF), I learned one thing and that was my results really came down to the start of me actually tracking my energy intake and macronutrients and making changes when fat loss stalled. It’s not magic but maybe thing’s like this fit in with your lifestyle and your not much of a breakfast kinda guy or girl, again it comes down to preference but don’t sweat if it’s not your preference.
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Garaulet, M., Gómez-Abellán, P., Alburquerque-Béjar, J. J., Lee, Y. C., Ordovás, J. M., & Scheer, F. A. (2013). Timing of food intake predicts weight loss effectiveness. International journal of obesity, 37(4), 604-611.
Morris, C. J., Aeschbach, D., & Scheer, F. A. (2012). Circadian system, sleep and endocrinology. Molecular and cellular endocrinology, 349(1), 91-104.
Pateyjohns, I. R., Brinkworth, G. D., Buckley, J. D., Noakes, M., & Clifton, P. M. (2006). Comparison of three bioelectrical impedance methods with DXA in overweight and obese men. Obesity, 14(11), 2064-2070.
Sofer, S., Eliraz, A., Kaplan, S., Voet, H., Fink, G., Kima, T., & Madar, Z. (2011). Greater weight loss and hormonal changes after 6 months diet with carbohydrates eaten mostly at dinner. Obesity, 19(10), 2006-2014.
Manini, T. M. (2010). Energy expenditure and aging. Ageing research reviews, 9(1), 1-11.
Jakubowicz, D., Froy, O., Wainstein, J., & Boaz, M. (2012). Meal timing and composition influence ghrelin levels, appetite scores and weight loss maintenance in overweight and obese adults. Steroids, 77(4), 323-331.
Keim, N. L., Van Loan, M. D., Horn, W. F., Barbieri, T. F., & Mayclin, P. L. (1997). Weight loss is greater with consumption of large morning meals and fat-free mass is preserved with large evening meals in women on a controlled weight reduction regimen. The Journal of nutrition, 127(1), 75-82.