Sweet taste does not increase caloric intake, says study

Cicerale, Riddell and Keast 2012 report that taste is important to choose food, however perceived sweetness intensity alone does not influence decisively food behaviours related to sugar consumption and dietary intake in adults. [1]

The authors studied the behaviour of 85 adults which tasted a sugar solution and rated the percepted sweetness. The study found no correlation between perceived sweetness and total caloric intake,  food behaviours relating to sugar consumption dietary intake and micronutrients.

Applied methodology
The study was based on the general labeled magnitude scale (gLMS)  to measure the perceived sweetness intensity. Applying one-way analysis of variance (ANOVA) no difference between sweetness and  importance of adding or not sugar to tea or coffee was found; the same results apply  for avoiding sugar-sweetened or fizzy drinks. Independent t-test analysis found no association between sweetness intensity and confectionery intake, selected fruit and vegetable intake.
The authors report that persons produced similar results rating tastes and sounds using  gLMS compared with magnitude matching, suggesting that the gLMS is valid for taste comparisons across nontasters, medium tasters, and supertasters.

The General Labeled Magnitude Scale (gLMS) [2]
Bartoshuk et al 2004 developed the General Labeled Magnitude Scale based on the LabeledMagnitude Scale of 1993. The gLMS is a continuous scale using “strongest imaginable of any kind” as the top rating too overcome ceiling effects. The authors explain that labeled scales  use adjective/adverb intensity descriptors such as  “very strong” rose odour, compared with a “very strong” headache, compressing or expanding the descriptor  to fit the domain of interest.

Magnitude matching
Magnitude matching asks a person to rate the intensities of taste stimuli and stimuli of another sensory system, such as the loudness of a tone, on a similar scale to overcome different perception intensities among subjects.

Other studies linking food taste and nutritional behaviour
The sensation of taste can be categorized into five basic tastes: sweet, bitter, sour, salty, and umami.

Fat identified as sixth human taste, discovery relevant for obesity management [3]
After discovering "umami" taste, scientists postulate that fat as a "sixth taste" with CD36 receptor  as responding signal to fat stimulus. CD 36  is located on the tongue and makes obese people to prefer foods with higher fat content, crave high fat foods more frequently  and consume more fat than lean individuals. Pepino et al. 2011 found that CD36 genes vary among different  rs1761667 genotypes (6 AA, 7 AG and 8 GG), influencing the perception of fat.

The homozygous A-allele (AA) lowers the expression of CD36. Subjects with the AA-allele had 8 fold higher detection thresholds for fat than subjects homozygous for the G-allele (GG). Heterozygous (AG) presented intermediate results. Detection threshold (sensitivity to fat) is increased by hydrolysis of triacylglycerols. Oleic acid was earlier detected than not hydrolysed fat. despite its higher viscosity.

The authors concluded that  taste rather than texture is the primary detection mechanism of taste of fat, having implications  in the regulation of food intake and obesity management.

Bitter taste: Bitter taste is linked to a reduction of fruits and vegetables intake in people reacting to natural bitter compounds.  6-n-propylthiouracil (PROP) a thionamide, tastes very bitter by some people, but tasteless by others depending on genetic makeup. Wooding et al. 2004 suggests that natural selection modified alleles at the PTC locus , resulting in  humans.“taster” and “nontaster”. [4]
Saltiness: Saltiness is a taste produced by sodium, potassium or lithium.
Sourness: Sourness is a response to acidity. the taste receptor PKD2L1 is involved in this response.
Umami:  The amino acid glutamic acid is responsible for umami. Some nucleotides like inosinic acid and guanylic acid enhancing the taste.

[1] Cicerale S, Riddell LJ, Keast RS: The Association between Perceived Sweetness Intensity and Dietary Intake in Young Adults. J Food Sci. 2012 Jan;77(1):H31-5. doi: 10.1111/j.1750-3841.2011.02473.x.
http://www.ncbi.nlm.nih.gov/pubmed/22132685

[2] Bartoshuk LM, Duffy VB, Green BG, Hoffman HJ, Ko CW, Lucchina LA, Marks LE, Snyder DJ, Weiffenbach JM: Valid across-group comparisons with labeled scales: the gLMS versus magnitude matching. Physiol Behav. 2004 Aug;82(1):109-14.
http://www.ncbi.nlm.nih.gov/pubmed/15234598

[3] Pepino MY, Love-Gregory L, Klein S, Abumrad NA.: The fatty acid translocase gene, CD36, and lingual lipase influence oral sensitivity to fat in obese subjects. J Lipid Res. 2011 Dec 31
http://www.ncbi.nlm.nih.gov/pubmed/22210925

[4] Wooding S, Kim UK, Bamshad MJ, Larsen J, Jorde LB, Drayna D: Natural selection and molecular evolution in PTC, a bitter-taste receptor gene. Am J Hum Genet. 2004 Apr;74(4):637-46.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1181941